Merge branch 'master' of github.com:bram85/topydo

25265e12 · Bram Schoenmakers · 12d7edf0 · 9d0f961b · 25265e12 · 25265e12
Commit 25265e12 authored Dec 16, 2016 by Bram Schoenmakers
52 changed files
--- a/.gitattributes
+++ b/.gitattributes
+test/data/* text eol=lf
+test/data/*.ics binary
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,7 +4,14 @@ python:
  - "3.3"
  - "3.4"
  - "3.5"
-  - "pypy3"
+env:
+  - GREEN_OPTS=
+matrix:
+  include:
+    - python: "pypy3"
+      env: GREEN_OPTS='--processes 1'
 install:
  - "python -m pip install pip --upgrade"
  - "pip install ."
@@ -15,7 +22,7 @@ install:
  - "pip install pylint"
  - "pip install codecov"
 script:
-  - "green -vvr"
+  - "green -vvr $GREEN_OPTS"
  - "python -m pylint --errors-only topydo test"
 # Cache Dependencies
 after_script:

--- a/CHANGES.md
+++ b/CHANGES.md
+0.11
+----
+* New: `ls` can group items with the `-g` flag, accepting a group expression
+  (which has the same format as a sort expression). To group items by project,
+  run: `topydo ls -g project`.
+* New: `ls` can print todo items in the Graphviz Dot format, such that
+  dependencies can be visualized. Use `ls -f dot`, or
+  `topydo ls -f dot +ProjectA | dot -Tsvg -o projectA.svg` to make a graph for
+  project A.
+* New: Focus and mark colors are customizable in the column UI (thanks to
+  @colinsullivan).
+* New: todo items can be hidden by adding a `h:1` tag (thanks to @MinchinWeb).
+* New: an alternative column definition file can be given with the `-l` flag:
+  `topydo columns -ls /path/to/columns.conf` (thanks to @mruwek).
+* Fix: column UI reloads automatically when the todo.txt file was changed
+  externally.
+* Fix: `edit` did not work on some operating systems (e.g. Mac OS X).
+* Fix: relative dates were sometimes one day off.
+* Fix: Minor importance calculation fix during the weekend for distant mondays
+  (thanks to @aetherknight).
+* Fix: tests were made more deterministic.
+* Change: Performance improvements for the column UI, it scales better with
+  large todo lists.
+* Change: temporary files (for editing) will be detected as todo.txt files by
+   the todo.txt-vim plugin.
 0.10.1
 ------

--- a/setup.py
+++ b/setup.py
@@ -20,6 +20,8 @@ def find_version(*file_paths):
        return version_match.group(1)
    raise RuntimeError("Unable to find version string.")
+WATCHDOG = 'watchdog >= 0.8.3'
 setup(
    name = "topydo",
    packages = find_packages(exclude=["test"]),
@@ -34,9 +36,9 @@ setup(
    extras_require = {
        ':sys_platform=="win32"': ['colorama>=0.2.5'],
        ':python_version=="3.2"': ['backports.shutil_get_terminal_size>=1.0.0'],
-        'columns': ['urwid >= 1.3.0'],
+        'columns': ['urwid >= 1.3.0', WATCHDOG],
        'ical': ['icalendar'],
-        'prompt': ['prompt_toolkit >= 0.53'],
+        'prompt': ['prompt_toolkit >= 0.53', WATCHDOG],
        'test': ['coverage', 'freezegun', 'green', ],
        'test:python_version=="3.2"': ['mock'],
    },

--- a/test/command_testcase.py
+++ b/test/command_testcase.py
@@ -14,6 +14,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
+import os
 from test.topydo_testcase import TopydoTest
 from topydo.lib.Utils import escape_ansi
@@ -27,12 +28,12 @@ class CommandTest(TopydoTest):
    def out(self, p_output):
        if isinstance(p_output, list) and p_output:
            self.output += escape_ansi(
-                "\n".join([str(s) for s in p_output]) + "\n")
+                os.linesep.join([str(s) for s in p_output]) + os.linesep)
        elif p_output:
-            self.output += str(p_output) + "\n"
+            self.output += str(p_output) + os.linesep
    def error(self, p_error):
        if isinstance(p_error, list) and p_error:
-            self.errors += escape_ansi(p_error + "\n") + "\n"
+            self.errors += escape_ansi(p_error + os.linesep) + os.linesep
        elif p_error:
-            self.errors += str(p_error) + "\n"
+            self.errors += str(p_error) + os.linesep
--- a/test/data/ColorsTest5.conf
+++ b/test/data/ColorsTest5.conf
@@ -4,3 +4,5 @@ project_color =
 context_color =
 link_color =
 metadata_color =
+focus_background_color =
+marked_background_color =
--- a/test/data/ConfigTest4.conf
+++ b/test/data/ConfigTest4.conf
@@ -24,3 +24,5 @@ project_color               = junk
 context_color               = junk
 metadata_color              = junk
 link_color                  = junk
+focus_background_color      = junk
+marked_background_color       = junk
--- a/test/data/ListCommandDotTest.txt
+++ b/test/data/ListCommandDotTest.txt
+(C) 2015-11-05 Foo @Context2 Not@Context +Project1 Not+Project due:2016-11-18 t:2016-11-17
+(D) Bar @Context1 +Project2 p:1
+(C) Baz @Context1 +Project1 key:value id:1
+(C) Drink beer @ home
+(C) 13 + 29 = 42
+x 2014-12-12 Completed but with date:2014-12-12
--- a/test/data/ListCommandGroupTest.txt
+++ b/test/data/ListCommandGroupTest.txt
+A only test:test_group1
+B only test:test_group1
+A and +B test:test_group1
+No project test:test_group1
+Different item test:test_group2 l:1
+Another item test:test_group2 l:0
+Test 1 due:2016-12-06 test:test_group3
+Test 2 due:2016-12-07 test:test_group3
+Test 1 t:2016-12-06 test:test_group4 test:test_group5
+Test 2 t:2016-12-07 test:test_group4 test:test_group5
+Group by non-existing tag test:test_group6
+Sort descending +A test:test_group7
+Sort descending +B test:test_group7
+Inner sort 1 +A @A test:test_group8
+Inner sort 2 +A @B test:test_group8
+Inner sort 3 +B @A test:test_group8
+Inner sort 4 +B @B test:test_group8
+Inner sort 1 +A test:test_group9
+Inner sort 2 +A test:test_group9
--- a/test/data/ListCommandTest.dot
+++ b/test/data/ListCommandTest.dot
+digraph topydo {
+node [ shape="none" margin="0" fontsize="9" fontname="Helvetica" ]
+  _1 [label=<<TABLE CELLBORDER="0" CELLSPACING="1" VALIGN="top"><TR><TD><B>1</B></TD><TD BALIGN="LEFT"><B>Foo @Context2 Not@Context +Project1<BR />Not+Project</B></TD></TR><HR/><TR><TD ALIGN="RIGHT">Prio:</TD><TD ALIGN="LEFT">C</TD></TR><TR><TD ALIGN="RIGHT">Starts:</TD><TD ALIGN="LEFT">2016-11-17 (today)</TD></TR><TR><TD ALIGN="RIGHT">Due:</TD><TD ALIGN="LEFT">2016-11-18 (in a day)</TD></TR></TABLE>> style=filled fillcolor="#008000" fontcolor="#ffffff"]
+  _3 [label=<<TABLE CELLBORDER="0" CELLSPACING="1" VALIGN="top"><TR><TD><B>3</B></TD><TD BALIGN="LEFT"><B>Baz @Context1 +Project1</B></TD></TR><HR/><TR><TD ALIGN="RIGHT">Prio:</TD><TD ALIGN="LEFT">C</TD></TR></TABLE>> style=filled fillcolor="#008000" fontcolor="#ffffff"]
+  _4 [label=<<TABLE CELLBORDER="0" CELLSPACING="1" VALIGN="top"><TR><TD><B>4</B></TD><TD BALIGN="LEFT"><B>Drink beer @ home</B></TD></TR><HR/><TR><TD ALIGN="RIGHT">Prio:</TD><TD ALIGN="LEFT">C</TD></TR></TABLE>> style=filled fillcolor="#008000" fontcolor="#ffffff"]
+  _5 [label=<<TABLE CELLBORDER="0" CELLSPACING="1" VALIGN="top"><TR><TD><B>5</B></TD><TD BALIGN="LEFT"><B>13 + 29 = 42</B></TD></TR><HR/><TR><TD ALIGN="RIGHT">Prio:</TD><TD ALIGN="LEFT">C</TD></TR></TABLE>> style=filled fillcolor="#008000" fontcolor="#ffffff"]
+  _2 [label=<<TABLE CELLBORDER="0" CELLSPACING="1" VALIGN="top"><TR><TD><B>2</B></TD><TD BALIGN="LEFT"><B>Bar @Context1 +Project2</B></TD></TR><HR/><TR><TD ALIGN="RIGHT">Prio:</TD><TD ALIGN="LEFT">D</TD></TR></TABLE>> style=filled fillcolor="#008000" fontcolor="#ffffff"]
+  _6 [label=<<TABLE CELLBORDER="0" CELLSPACING="1" VALIGN="top"><TR><TD><B>6</B></TD><TD BALIGN="LEFT"><B><S>Completed but with</S></B></TD></TR></TABLE>> style=filled fillcolor="#008000" fontcolor="#ffffff"]
+  _3 -> _2
+  _1 -> _4 [style="invis"]
+  _4 -> _5 [style="invis"]
+  _5 -> _6 [style="invis"]
+}
--- a/test/data/ListCommandTest.txt
+++ b/test/data/ListCommandTest.txt
@@ -5,3 +5,4 @@
 (C) 13 + 29 = 42
 x 2014-12-12 Completed but with date:2014-12-12
+hidden item h:1
--- a/test/data/SorterTest1-result.txt
+++ b/test/data/SorterTest1-result.txt
-First
+first
 (A) Foo
 2014-06-14 Last
--- a/test/data/SorterTest1.txt
+++ b/test/data/SorterTest1.txt
 (A) Foo
 2014-06-14 Last
-First
+first
--- a/test/facilities.py
+++ b/test/facilities.py
@@ -14,7 +14,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
-from topydo.lib.PrettyPrinter import PrettyPrinter
+from topydo.lib.printers.PrettyPrinter import PrettyPrinter
 from topydo.lib.Todo import Todo
 from topydo.lib.TodoFile import TodoFile
 from topydo.lib.TodoList import TodoList

--- a/test/test_colors.py
+++ b/test/test_colors.py
@@ -154,6 +154,14 @@ class ColorsTest(TopydoTest):
        self.assertEqual(color_b, '')
        self.assertEqual(color_c, '')
+    def test_focus_color(self):
+        config(p_overrides={('colorscheme', 'focus_background_color'): 'gray'})
+        self.assertEqual(config().focus_background_color().as_ansi(), '\033[0;37m')
+    def test_mark_color(self):
+        config(p_overrides={('colorscheme', 'marked_background_color'): 'blue'})
+        self.assertEqual(config().marked_background_color().as_ansi(), '\033[0;34m')
    def test_empty_color_values(self):
        config("test/data/ColorsTest5.conf")
        project_color = config().project_color().as_ansi(p_decoration='bold')

--- a/test/test_config.py
+++ b/test/test_config.py
@@ -128,6 +128,18 @@ class ConfigTest(TopydoTest):
        self.assertEqual(config("test/data/ConfigTest5.conf").link_color().color, 6)
    def test_config24(self):
+        """ No focus background color value. """
+        self.assertEqual(config("test/data/ConfigTest5.conf").focus_background_color().color, 7)
+    def test_config25(self):
+        """ No mark background color value. """
+        self.assertEqual(config("test/data/ConfigTest5.conf").marked_background_color().color, 4)
+    def test_config26(self):
+        self.assertTrue(config("test/data/ConfigTest4.conf").focus_background_color().is_neutral())
+        self.assertTrue(config("test/data/ConfigTest4.conf").marked_background_color().is_neutral())
+    def test_config27(self):
        """ column_keymap test. """
        keymap, keystates = config("test/data/ConfigTest6.conf").column_keymap()

--- a/test/test_dep_command.py
+++ b/test/test_dep_command.py
@@ -295,6 +295,39 @@ class DepCommandTest(CommandTest):
        self.assertEqual(self.output, "")
        self.assertEqual(self.errors, command.usage() + "\n")
+    def test_dot1(self):
+        command = DepCommand(["dot"], self.todolist, self.out, self.error)
+        command.execute()
+        self.assertFalse(self.todolist.dirty)
+        self.assertEqual(self.output, "")
+        self.assertEqual(self.errors, command.usage() + "\n")
+    def test_dot2(self):
+        self.maxDiff = None
+        command = DepCommand(["dot", "1"], self.todolist, self.out, self.error)
+        command.execute()
+        self.assertFalse(self.todolist.dirty)
+        self.assertEqual(self.output, """digraph topydo {
+node [ shape="none" margin="0" fontsize="9" fontname="Helvetica" ]
+  _2 [label=<<TABLE CELLBORDER="0" CELLSPACING="1" VALIGN="top"><TR><TD><B>2</B></TD><TD BALIGN="LEFT"><B>Bar</B></TD></TR></TABLE>> style=filled fillcolor="#008000" fontcolor="#ffffff"]
+  _3 [label=<<TABLE CELLBORDER="0" CELLSPACING="1" VALIGN="top"><TR><TD><B>3</B></TD><TD BALIGN="LEFT"><B>Baz</B></TD></TR></TABLE>> style=filled fillcolor="#008000" fontcolor="#ffffff"]
+  _1 [label=<<TABLE CELLBORDER="0" CELLSPACING="1" VALIGN="top"><TR><TD><B>1</B></TD><TD BALIGN="LEFT"><B>Foo</B></TD></TR></TABLE>> style=filled fillcolor="#008000" fontcolor="#ffffff"]
+  _1 -> _2
+  _1 -> _3
+}\n
+""")
+        self.assertEqual(self.errors, "")
+    def test_dot3(self):
+        command = DepCommand(["dot", "99"], self.todolist, self.out, self.error)
+        command.execute()
+        self.assertFalse(self.todolist.dirty)
+        self.assertEqual(self.output, "")
+        self.assertEqual(self.errors, "Invalid todo number given." + "\n")
    def gc_helper(self, p_subcommand):
        command = DepCommand([p_subcommand], self.todolist, self.out,
                             self.error)

--- a/test/test_importance.py
+++ b/test/test_importance.py
@@ -56,5 +56,39 @@ class ImportanceTest(TopydoTest):
        todo = Todo("(C) Foo " + config().tag_due() + ":" + "2015-11-09")
        self.assertEqual(importance(todo), 6)
+@freeze_time("2016, 10, 21")
+class ImportanceWeekendFridayTest(TopydoTest):
+    def test_importance_ignore_weekends_due_not_next_monday(self):
+        # Today is friday
+        # due on a monday, but over a month away.
+        # So 2 + 0 (no priority) + 0 (no star) + 0 (due > 14 days)
+        config(p_overrides={('sort', 'ignore_weekends'): '1'})
+        todo = Todo("Foo " + config().tag_due() + ":" + "2016-11-28")
+        self.assertEqual(importance(todo), 2)
+@freeze_time("2016, 10, 22")
+class ImportanceWeekendSaturdayTest(TopydoTest):
+    def test_importance_ignore_weekends_due_not_next_monday(self):
+        # Today is saturday
+        # due on a monday, but over a month away.
+        # So 2 + 0 (no priority) + 0 (no star) + 0 (due > 14 days)
+        config(p_overrides={('sort', 'ignore_weekends'): '1'})
+        todo = Todo("Foo " + config().tag_due() + ":" + "2016-11-28")
+        self.assertEqual(importance(todo), 2)
+@freeze_time("2016, 10, 23")
+class ImportanceWeekendSundayTest(TopydoTest):
+    def test_importance_ignore_weekends_due_not_next_monday(self):
+        # Today is sunday
+        # due on a monday, but over a month away.
+        # So 2 + 0 (no priority) + 0 (no star) + 0 (due > 14 days)
+        config(p_overrides={('sort', 'ignore_weekends'): '1'})
+        todo = Todo("Foo " + config().tag_due() + ":" + "2016-11-28")
+        self.assertEqual(importance(todo), 2)
 if __name__ == '__main__':
    unittest.main()
--- a/test/test_json_printer.py
+++ b/test/test_json_printer.py
@@ -17,7 +17,7 @@
 import unittest
 from test.topydo_testcase import TopydoTest
-from topydo.lib.JsonPrinter import JsonPrinter
+from topydo.lib.printers.Json import JsonPrinter
 from topydo.lib.Todo import Todo

--- a/test/test_list_command.py
+++ b/test/test_list_command.py
--- a/test/test_sort_command.py
+++ b/test/test_sort_command.py
@@ -33,14 +33,14 @@ class SortCommandTest(CommandTest):
        command.execute()
        self.assertEqual(self.todolist.print_todos(),
-                         "First\n(A) Foo\n2014-06-14 Last")
+                         "first\n(A) Foo\n2014-06-14 Last")
    def test_sort2(self):
        command = SortCommand([], self.todolist, self.out, self.error)
        command.execute()
        self.assertEqual(self.todolist.print_todos(),
-                         "(A) Foo\n2014-06-14 Last\nFirst")
+                         "(A) Foo\n2014-06-14 Last\nfirst")
    def test_sort3(self):
        """ Check that order does not influence the UID of a todo. """

--- a/topydo.conf
+++ b/topydo.conf
@@ -50,6 +50,8 @@ append_parent_contexts      = 0
 ; context_color = magenta
 ; metadata_color = green
 ; link_color = light-cyan
+; focus_background_color = gray
+; marked_background_color = blue
 [aliases]
 ;showall = ls -x

--- a/topydo/commands/DepCommand.py
+++ b/topydo/commands/DepCommand.py
@@ -17,7 +17,8 @@
 from topydo.lib import Filter
 from topydo.lib.Command import Command, InvalidCommandArgument
 from topydo.lib.Config import config
-from topydo.lib.PrettyPrinter import pretty_printer_factory
+from topydo.lib.printers.Dot import DotPrinter
+from topydo.lib.printers.PrettyPrinter import pretty_printer_factory
 from topydo.lib.Sorter import Sorter
 from topydo.lib.TodoListBase import InvalidTodoException
 from topydo.lib.View import View
@@ -130,6 +131,26 @@ class DepCommand(Command):
        except InvalidCommandArgument:
            self.error(self.usage())
+    def _handle_dot(self):
+        """ Handles the dot subsubcommand. """
+        self.printer = DotPrinter(self.todolist)
+        try:
+            arg = self.argument(1)
+            todo = self.todolist.todo(arg)
+            arg = self.argument(1)
+            todos = set([self.todolist.todo(arg)])
+            todos |= set(self.todolist.children(todo))
+            todos |= set(self.todolist.parents(todo))
+            todos = sorted(todos, key=lambda t: t.text())
+            self.out(self.printer.print_list(todos))
+        except InvalidTodoException:
+            self.error("Invalid todo number given.")
+        except InvalidCommandArgument:
+            self.error(self.usage())
    def execute(self):
        if not super().execute():
            return False
@@ -140,6 +161,7 @@ class DepCommand(Command):
            'del':   self._handle_rm,
            'ls':    self._handle_ls,
            'clean': self.todolist.clean_dependencies,
+            'dot':   self._handle_dot,
            'gc':    self.todolist.clean_dependencies,
        }
@@ -154,6 +176,7 @@ class DepCommand(Command):
  dep add <NUMBER> <before|partof|after|parents-of|children-of> <NUMBER>
  dep ls <NUMBER> to
  dep ls to <NUMBER>
+  dep dot <NUMBER>
  dep clean"""
    def help(self):
@@ -163,5 +186,6 @@ class DepCommand(Command):
                      item 1.
 * rm (alias: del)   : Removes a dependency.
 * ls                : Lists all dependencies to or from a certain todo.
+* dot               : Prints a dependency tree as a Dot graph.
 * clean (alias: gc) : Removes redundant id or p tags.\
 """
--- a/topydo/commands/DoCommand.py
+++ b/topydo/commands/DoCommand.py
@@ -17,7 +17,7 @@
 from datetime import date
 from topydo.lib.DCommand import DCommand
-from topydo.lib.PrettyPrinter import PrettyPrinter
+from topydo.lib.printers.PrettyPrinter import PrettyPrinter
 from topydo.lib.prettyprinters.Numbers import PrettyPrinterNumbers
 from topydo.lib.Recurrence import NoRecurrenceException, advance_recurring_todo
 from topydo.lib.RelativeDate import relative_date_to_date

--- a/topydo/commands/EditCommand.py
+++ b/topydo/commands/EditCommand.py
@@ -15,6 +15,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 import os
+import codecs
 import tempfile
 from subprocess import CalledProcessError, check_call
@@ -54,16 +55,16 @@ class EditCommand(MultiCommand):
            self.multi_mode = False
    def _todos_to_temp(self):
-        f = tempfile.NamedTemporaryFile()
+        f = tempfile.NamedTemporaryFile(delete=False, suffix='.todo.txt')
        for todo in self.todos:
            f.write((todo.source() + "\n").encode('utf-8'))
-        f.seek(0)
+        f.close()
        return f
    def _todos_from_temp(self, p_temp_file):
-        p_temp_file.seek(0)
+        f = codecs.open(p_temp_file.name, encoding='utf-8')
-        todos = p_temp_file.read().decode('utf-8').splitlines()
+        todos = f.read().splitlines()
        todo_objs = []
        for todo in todos:
@@ -121,6 +122,8 @@ class EditCommand(MultiCommand):
        else:
            self.error(self.usage())
+        os.unlink(temp_todos.name)
    def _execute_not_multi(self):
        if self.edit_archive:
            archive = config().archive()

--- a/topydo/commands/ListCommand.py
+++ b/topydo/commands/ListCommand.py
@@ -20,11 +20,13 @@ import os
 from topydo.lib.Config import config
 from topydo.lib.ExpressionCommand import ExpressionCommand
-from topydo.lib.Filter import InstanceFilter
+from topydo.lib.Filter import HiddenTagFilter, InstanceFilter
-from topydo.lib.PrettyPrinter import pretty_printer_factory
+from topydo.lib.printers.PrettyPrinter import pretty_printer_factory
 from topydo.lib.prettyprinters.Format import PrettyPrinterFormatFilter
 from topydo.lib.TodoListBase import InvalidTodoException
+from topydo.lib.Sorter import Sorter
 from topydo.lib.Utils import get_terminal_size
+from topydo.lib.View import View
 class ListCommand(ExpressionCommand):
@@ -37,6 +39,7 @@ class ListCommand(ExpressionCommand):
        self.printer = None
        self.sort_expression = config().sort_string()
+        self.group_expression = config().group_string()
        self.show_all = False
        self.ids = None
        self.format = config().list_format()
@@ -55,7 +58,7 @@ class ListCommand(ExpressionCommand):
        return True
    def _process_flags(self):
-        opts, args = self.getopt('f:F:i:n:Ns:x')
+        opts, args = self.getopt('f:F:g:i:n:Ns:x')
        for opt, value in opts:
            if opt == '-x':
@@ -64,16 +67,25 @@ class ListCommand(ExpressionCommand):
                self.sort_expression = value
            elif opt == '-f':
                if value == 'json':
-                    from topydo.lib.JsonPrinter import JsonPrinter
+                    from topydo.lib.printers.Json import JsonPrinter
                    self.printer = JsonPrinter()
                elif value == 'ical':
                    if self._poke_icalendar():
-                        from topydo.lib.IcalPrinter import IcalPrinter
+                        from topydo.lib.printers.Ical import IcalPrinter
                        self.printer = IcalPrinter(self.todolist)
+                elif value == 'dot':
+                    from topydo.lib.printers.Dot import DotPrinter
+                    self.printer = DotPrinter(self.todolist)
+                    # a graph without dependencies is not so useful, hence
+                    # show all
+                    self.show_all = True
                else:
                    self.printer = None
            elif opt == '-F':
                self.format = value
+            elif opt == '-g':
+                self.group_expression = value
            elif opt == '-N':
                # 2 lines are assumed to be taken up by printing the next prompt
                # display at least one item
@@ -93,8 +105,9 @@ class ListCommand(ExpressionCommand):
    def _filters(self):
        """
-        Additional filters to select particular todo items given with the -i
+        Additional filters to:
-        flag.
+            - select particular todo items given with the -i flag,
+            - hide appropriately tagged items in the absense of the -x flag.
        """
        filters = super()._filters()
@@ -112,6 +125,9 @@ class ListCommand(ExpressionCommand):
            todos = [get_todo(i) for i in self.ids]
            filters.append(InstanceFilter(todos))
+        if not self.show_all:
+            filters.append(HiddenTagFilter())
        return filters
    def _print(self):
@@ -132,7 +148,16 @@ class ListCommand(ExpressionCommand):
            self.printer = pretty_printer_factory(self.todolist, filters)
-        self.out(self.printer.print_list(self._view().todos))
+        if self.group_expression:
+            self.out(self.printer.print_groups(self._view().groups))
+        else:
+            self.out(self.printer.print_list(self._view().todos))
+    def _view(self):
+        sorter = Sorter(self.sort_expression, self.group_expression)
+        filters = self._filters()
+        return View(sorter, filters, self.todolist)
    def _N_lines(self):
        ''' Determine how many lines to print, such that the number of items
@@ -179,9 +204,9 @@ class ListCommand(ExpressionCommand):
        return True
    def usage(self):
-        return """Synopsis: ls [-x] [-s <SORT EXPRESSION>] [-f <OUTPUT FORMAT>]
+        return """Synopsis: ls [-x] [-s <SORT EXPRESSION>]
-[-F <FORMAT STRING>] [-i <NUMBER 1>[,<NUMBER 2> ...]] [-N | -n <INTEGER>]
+[-g <GROUP EXPRESSION>] [-f <OUTPUT FORMAT>] [-F <FORMAT STRING>]
-[EXPRESSION]"""
+[-i <NUMBER 1>[,<NUMBER 2> ...]] [-N | -n <INTEGER>] [EXPRESSION]"""
    def help(self):
        return """\
@@ -193,9 +218,12 @@ Lists all relevant todos. A todo is relevant when:
 When an EXPRESSION is given, only the todos matching that EXPRESSION are shown.
-f : Specify the OUTPUT FORMAT, being 'text' (default), 'ical' or 'json'.
+-f : Specify the OUTPUT format, being 'text' (default), 'dot' or 'ical' or
+     'json'.
     * 'text' - Text output with colors and indentation if applicable.
+     * 'dot'  - Prints a dependency graph for the selected items in GraphViz
+                Dot format.
     * 'ical' - iCalendar (RFC 2445). Is not supported in Python 3.2. Be aware
                that this is not a read-only operation, todo items may obtain
                an 'ical' tag with a unique ID. Completed todo items may be
@@ -233,10 +261,14 @@ When an EXPRESSION is given, only the todos matching that EXPRESSION are shown.
     (empty string) when an item has no priority set.
     A tab character serves as a marker to start right alignment.
+-g : Group items according to a GROUP EXPRESSION. A group expression is similar
+     to a sort expression. Defaults to the group expression in the
+     configuration.
 -i : Comma separated list of todo IDs to print.
 -n : Number of items to display. Defaults to the value in the configuration.
 -N : Limit number of items displayed such that they fit on the terminal.
-s : Sort the list according to a SORT EXPRESSION. Defaults to the expression
+-s : Sort the list according to a SORT EXPRESSION. Defaults to the sort
-     in the configuration.
+     expression in the configuration.
-x : Show all todos (i.e. do not filter on dependencies or relevance).\
+-x : Show all todos (i.e. do not filter on dependencies, relevance, or hidden
+     status).\
 """
--- a/topydo/lib/Color.py
+++ b/topydo/lib/Color.py
@@ -45,6 +45,62 @@ class Color:
        'white': 15,
    }
+    # Source: https://gist.github.com/jasonm23/2868981
+    html_color_dict = {
+          0: "#000000",   1: "#800000",   2: "#008000",   3: "#808000",   4: "#000080",
+          5: "#800080",   6: "#008080",   7: "#c0c0c0",   8: "#808080",   9: "#ff0000",
+         10: "#00ff00",  11: "#ffff00",  12: "#0000ff",  13: "#ff00ff",  14: "#00ffff",
+         15: "#ffffff",  16: "#000000",  17: "#00005f",  18: "#000087",  19: "#0000af",
+         20: "#0000d7",  21: "#0000ff",  22: "#005f00",  23: "#005f5f",  24: "#005f87",
+         25: "#005faf",  26: "#005fd7",  27: "#005fff",  28: "#008700",  29: "#00875f",
+         30: "#008787",  31: "#0087af",  32: "#0087d7",  33: "#0087ff",  34: "#00af00",
+         35: "#00af5f",  36: "#00af87",  37: "#00afaf",  38: "#00afd7",  39: "#00afff",
+         40: "#00d700",  41: "#00d75f",  42: "#00d787",  43: "#00d7af",  44: "#00d7d7",
+         45: "#00d7ff",  46: "#00ff00",  47: "#00ff5f",  48: "#00ff87",  49: "#00ffaf",
+         50: "#00ffd7",  51: "#00ffff",  52: "#5f0000",  53: "#5f005f",  54: "#5f0087",
+         55: "#5f00af",  56: "#5f00d7",  57: "#5f00ff",  58: "#5f5f00",  59: "#5f5f5f",
+         60: "#5f5f87",  61: "#5f5faf",  62: "#5f5fd7",  63: "#5f5fff",  64: "#5f8700",
+         65: "#5f875f",  66: "#5f8787",  67: "#5f87af",  68: "#5f87d7",  69: "#5f87ff",
+         70: "#5faf00",  71: "#5faf5f",  72: "#5faf87",  73: "#5fafaf",  74: "#5fafd7",
+         75: "#5fafff",  76: "#5fd700",  77: "#5fd75f",  78: "#5fd787",  79: "#5fd7af",
+         80: "#5fd7d7",  81: "#5fd7ff",  82: "#5fff00",  83: "#5fff5f",  84: "#5fff87",
+         85: "#5fffaf",  86: "#5fffd7",  87: "#5fffff",  88: "#870000",  89: "#87005f",
+         90: "#870087",  91: "#8700af",  92: "#8700d7",  93: "#8700ff",  94: "#875f00",
+         95: "#875f5f",  96: "#875f87",  97: "#875faf",  98: "#875fd7",  99: "#875fff",
+        100: "#878700", 101: "#87875f", 102: "#878787", 103: "#8787af", 104: "#8787d7",
+        105: "#8787ff", 106: "#87af00", 107: "#87af5f", 108: "#87af87", 109: "#87afaf",
+        110: "#87afd7", 111: "#87afff", 112: "#87d700", 113: "#87d75f", 114: "#87d787",
+        115: "#87d7af", 116: "#87d7d7", 117: "#87d7ff", 118: "#87ff00", 119: "#87ff5f",
+        120: "#87ff87", 121: "#87ffaf", 122: "#87ffd7", 123: "#87ffff", 124: "#af0000",
+        125: "#af005f", 126: "#af0087", 127: "#af00af", 128: "#af00d7", 129: "#af00ff",
+        130: "#af5f00", 131: "#af5f5f", 132: "#af5f87", 133: "#af5faf", 134: "#af5fd7",
+        135: "#af5fff", 136: "#af8700", 137: "#af875f", 138: "#af8787", 139: "#af87af",
+        140: "#af87d7", 141: "#af87ff", 142: "#afaf00", 143: "#afaf5f", 144: "#afaf87",
+        145: "#afafaf", 146: "#afafd7", 147: "#afafff", 148: "#afd700", 149: "#afd75f",
+        150: "#afd787", 151: "#afd7af", 152: "#afd7d7", 153: "#afd7ff", 154: "#afff00",
+        155: "#afff5f", 156: "#afff87", 157: "#afffaf", 158: "#afffd7", 159: "#afffff",
+        160: "#d70000", 161: "#d7005f", 162: "#d70087", 163: "#d700af", 164: "#d700d7",
+        165: "#d700ff", 166: "#d75f00", 167: "#d75f5f", 168: "#d75f87", 169: "#d75faf",
+        170: "#d75fd7", 171: "#d75fff", 172: "#d78700", 173: "#d7875f", 174: "#d78787",
+        175: "#d787af", 176: "#d787d7", 177: "#d787ff", 178: "#dfaf00", 179: "#dfaf5f",
+        180: "#dfaf87", 181: "#dfafaf", 182: "#dfafdf", 183: "#dfafff", 184: "#dfdf00",
+        185: "#dfdf5f", 186: "#dfdf87", 187: "#dfdfaf", 188: "#dfdfdf", 189: "#dfdfff",
+        190: "#dfff00", 191: "#dfff5f", 192: "#dfff87", 193: "#dfffaf", 194: "#dfffdf",
+        195: "#dfffff", 196: "#ff0000", 197: "#ff005f", 198: "#ff0087", 199: "#ff00af",
+        200: "#ff00df", 201: "#ff00ff", 202: "#ff5f00", 203: "#ff5f5f", 204: "#ff5f87",
+        205: "#ff5faf", 206: "#ff5fdf", 207: "#ff5fff", 208: "#ff8700", 209: "#ff875f",
+        210: "#ff8787", 211: "#ff87af", 212: "#ff87df", 213: "#ff87ff", 214: "#ffaf00",
+        215: "#ffaf5f", 216: "#ffaf87", 217: "#ffafaf", 218: "#ffafdf", 219: "#ffafff",
+        220: "#ffdf00", 221: "#ffdf5f", 222: "#ffdf87", 223: "#ffdfaf", 224: "#ffdfdf",
+        225: "#ffdfff", 226: "#ffff00", 227: "#ffff5f", 228: "#ffff87", 229: "#ffffaf",
+        230: "#ffffdf", 231: "#ffffff", 232: "#080808", 233: "#121212", 234: "#1c1c1c",
+        235: "#262626", 236: "#303030", 237: "#3a3a3a", 238: "#444444", 239: "#4e4e4e",
+        240: "#585858", 241: "#626262", 242: "#6c6c6c", 243: "#767676", 244: "#808080",
+        245: "#8a8a8a", 246: "#949494", 247: "#9e9e9e", 248: "#a8a8a8", 249: "#b2b2b2",
+        250: "#bcbcbc", 251: "#c6c6c6", 252: "#d0d0d0", 253: "#dadada", 254: "#e4e4e4",
+        255: "#eeeeee",
+    }
    def __init__(self, p_value=None):
        """ p_value is user input, be it a word color or an xterm code """
        self._value = None
@@ -117,3 +173,21 @@ class Color:
            color
        )
+    def as_html(self):
+        try:
+            return Color.html_color_dict[self.color]
+        except KeyError:
+            return '#ffffff'
+    def as_rgb(self):
+        """
+        Returns a tuple (r, g, b) of the color.
+        """
+        html = self.as_html()
+        return (
+            int(html[1:3], 16),
+            int(html[3:5], 16),
+            int(html[5:7], 16)
+        )
--- a/topydo/lib/Command.py
+++ b/topydo/lib/Command.py
@@ -16,7 +16,7 @@
 import getopt
-from topydo.lib.PrettyPrinter import PrettyPrinter
+from topydo.lib.printers.PrettyPrinter import PrettyPrinter
 class InvalidCommandArgument(Exception):

--- a/topydo/lib/Config.py
+++ b/topydo/lib/Config.py
@@ -77,6 +77,7 @@ class _Config:
            'ls': {
                'hide_tags': 'id,p,ical',
+                'hidden_item_tags': 'h,hide',
                'indent': '0',
                'list_limit': '-1',
                'list_format': '|%I| %x %{(}p{)} %c %s %k %{due:}d %{t:}t',
@@ -91,6 +92,7 @@ class _Config:
            'sort': {
                'keep_sorted': '0',
                'sort_string': 'desc:importance,due,desc:priority',
+                'group_string': '',
                'ignore_weekends': '1',
            },
@@ -105,6 +107,8 @@ class _Config:
                'metadata_color': 'green',
                'link_color': 'cyan',
                'priority_colors': 'A:cyan,B:yellow,C:blue',
+                'focus_background_color': 'gray',
+                'marked_background_color': 'blue'
            },
            'aliases': {
@@ -269,6 +273,9 @@ class _Config:
    def sort_string(self):
        return self.cp.get('sort', 'sort_string')
+    def group_string(self):
+        return self.cp.get('sort', 'group_string')
    def ignore_weekends(self):
        try:
            return self.cp.getboolean('sort', 'ignore_weekends')
@@ -311,6 +318,13 @@ class _Config:
        return [] if hidden_tags == '' else [tag.strip() for tag in
                                             hidden_tags.split(',')]
+    def hidden_item_tags(self):
+        """ Returns a list of tags which hide an item from the 'ls' output. """
+        hidden_item_tags = self.cp.get('ls', 'hidden_item_tags')
+        # pylint: disable=no-member
+        return [] if hidden_item_tags == '' else [tag.strip() for tag in
+                                                  hidden_item_tags.split(',')]
    def priority_color(self, p_priority):
        """
        Returns a dict with priorities as keys and color numbers as value.
@@ -359,6 +373,18 @@ class _Config:
        except ValueError:
            return Color(self.cp.get('colorscheme', 'link_color'))
+    def focus_background_color(self):
+        try:
+            return Color(self.cp.getint('colorscheme', 'focus_background_color'))
+        except ValueError:
+            return Color(self.cp.get('colorscheme', 'focus_background_color'))
+    def marked_background_color(self):
+        try:
+            return Color(self.cp.getint('colorscheme', 'marked_background_color'))
+        except ValueError:
+            return Color(self.cp.get('colorscheme', 'marked_background_color'))
    def auto_creation_date(self):
        try:
            return self.cp.getboolean('add', 'auto_creation_date')

--- a/topydo/lib/DCommand.py
+++ b/topydo/lib/DCommand.py
@@ -17,7 +17,7 @@
 import re
 from topydo.lib.MultiCommand import MultiCommand
-from topydo.lib.PrettyPrinter import PrettyPrinter
+from topydo.lib.printers.PrettyPrinter import PrettyPrinter
 from topydo.lib.prettyprinters.Numbers import PrettyPrinterNumbers

--- a/topydo/lib/Filter.py
+++ b/topydo/lib/Filter.py
@@ -16,6 +16,7 @@
 import re
+from topydo.lib.Config import config
 from topydo.lib.RelativeDate import relative_date_to_date
 from topydo.lib.Utils import date_string_to_date
@@ -91,8 +92,8 @@ class RelevanceFilter(Filter):
    The item has not been completed AND
    The start date is blank, today or in the past, AND
-    The priority is 'A' or the priority is B with due date within 30 days or
+    The priority is 'A', or the priority is 'B' with due date within 30 days, or
-    the priority is C with due date within 14 days.
+    the priority is 'C' with due date within 14 days.
    """
    def match(self, p_todo):
@@ -154,6 +155,28 @@ class InstanceFilter(Filter):
            return False
+class HiddenTagFilter(Filter):
+    def __init__(self):
+        """
+        Constructor.
+        A filter which hides items marked with the approriate tag.
+        """
+        super().__init__()
+    def match(self, p_todo):
+        """
+        Returns True when p_todo doesn't have a tag to mark it as hidden.
+        """
+        for my_tag in config().hidden_item_tags():
+            my_values = p_todo.tag_values(my_tag)
+            for my_value in my_values:
+                if not my_value in (0, '0', False, 'False'):
+                    return False
+        return True
 class LimitFilter(Filter):
    def __init__(self, p_limit):
        super().__init__()

--- a/topydo/lib/Importance.py
+++ b/topydo/lib/Importance.py
@@ -31,12 +31,14 @@ IMPORTANCE_VALUE = {'A': 3, 'B': 2, 'C': 1}
 def is_due_next_monday(p_todo):
-    """ Returns True when the given task is due next Monday. """
+    """ Returns True when today is Friday (or the weekend) and the given task
+    is due next Monday.
+    """
    today = date.today()
    due = p_todo.due_date()
    return due and due.weekday() == 0 and today.weekday() >= 4 and \
-        p_todo.days_till_due()
+        p_todo.days_till_due() <= 3
 def importance(p_todo, p_ignore_weekend=config().ignore_weekends()):

--- a/topydo/lib/ListFormat.py
+++ b/topydo/lib/ListFormat.py
@@ -21,7 +21,7 @@ import re
 from topydo.lib.Config import config
 from topydo.lib.ProgressColor import progress_color
-from topydo.lib.Utils import get_terminal_size, escape_ansi
+from topydo.lib.Utils import get_terminal_size, escape_ansi, humanize_date
 MAIN_PATTERN = (r'^({{(?P<before>.+?)}})?'
                r'(?P<placeholder>{ph}|\[{ph}\])'
@@ -39,12 +39,6 @@ def _filler(p_str, p_len):
    to_fill = p_len - len(p_str)
    return to_fill*' ' + p_str
-def humanize_date(p_datetime):
-    """ Returns a relative date string from a datetime object. """
-    now = arrow.now()
-    date = now.replace(day=p_datetime.day, month=p_datetime.month, year=p_datetime.year)
-    return date.humanize().replace('just now', 'today')
 def humanize_dates(p_due=None, p_start=None, p_creation=None):
    """
    Returns string with humanized versions of p_due, p_start and p_creation.

--- a/topydo/lib/Sorter.py
+++ b/topydo/lib/Sorter.py
@@ -16,56 +16,110 @@
 """ This module provides functionality to sort lists with todo items. """
+from collections import OrderedDict, namedtuple
+from itertools import groupby
 import re
 from datetime import date
+from topydo.lib.Config import config
 from topydo.lib.Importance import average_importance, importance
+from topydo.lib.Utils import humanize_date
-def is_priority_field(p_field):
+Field = namedtuple('Field', ['sort', 'group', 'label'])
-    """ Returns True when the field name denotes the priority. """
-    return p_field.startswith('prio')
+FIELDS = {
-def get_field_function(p_field):
+    'completed': Field(
-    """
+        # when a task has no completion date, push it to the end by assigning it
-    Given a property (string) of a todo, return a function that attempts to
+        # the maximum possible date.
-    access that property. If the property could not be located, return the
+        sort=(lambda t: t.completion_date() if t.completion_date() else date.max),
-    identity function.
+        group=(lambda t: humanize_date(t.completion_date()) if t.completion_date() else 'None'),
-    """
+        label='Completed',
-    result = lambda a: a
+    ),
+    'context': Field(
-    if is_priority_field(p_field):
+        sort=lambda t: sorted(c.lower() for c in t.contexts()) or ['zz'],
-        # assign dummy priority when a todo has no priority
+        group=lambda t: sorted(t.contexts()) or ['None'],
-        result = lambda a: a.priority() or 'ZZ'
+        label='Context'
-    elif p_field == 'context' or p_field == 'contexts':
+    ),
-        result = lambda a: sorted([c.lower() for c in a.contexts()])
+    'created': Field(
-    elif p_field == 'creationdate' or p_field == 'creation':
        # when a task has no creation date, push it to the end by assigning it
        # the maximum possible date.
-        result = (lambda a: a.creation_date() if a.creation_date()
+        sort=(lambda t: t.creation_date() if t.creation_date() else date.max),
-                  else date.max)
+        group=(lambda t: humanize_date(t.creation_date()) if t.creation_date() else 'None'),
-    elif p_field == 'done' or p_field == 'completed' or p_field == 'completion':
+        label='Created',
-        result = (lambda a: a.completion_date() if a.completion_date()
+    ),
-                  else date.max)
+    'importance': Field(
-    elif p_field == 'importance':
+        sort=importance,
-        result = importance
+        group=importance,
-    elif p_field == 'importance-avg' or p_field == 'importance-average':
+        label='Importance',
-        result = average_importance
+    ),
-    elif p_field == 'length':
+    'importance-avg': Field(
-        result = lambda a: a.length()
+        sort= average_importance,
-    elif p_field == 'project' or p_field == 'projects':
+        group=lambda t: round(average_importance(t), 1),
-        result = lambda a: sorted([c.lower() for c in a.projects()])
+        label='Importance (avg)',
-    elif p_field == 'text':
+    ),
-        result = lambda a: a.text()
+    'length': Field(
-    else:
+        sort=lambda t: t.length(),
-        # try to find the corresponding tag
+        group=lambda t: t.length(),
-        # when a tag is not present, push it to the end of the list by giving
+        label='Length',
-        # it an artificially higher value
+    ),
-        result = (lambda a: "0" + a.tag_value(p_field) if a.has_tag(p_field)
+    'priority': Field(
-                  else "1")
+        sort=(lambda t: t.priority() or 'ZZ'),
+        group=(lambda t: t.priority() or 'None'),
-    return result
+        label='Priority',
+    ),
+    'project': Field(
+        sort=lambda t: sorted(p.lower() for p in t.projects()) or ['zz'],
+        group=lambda t: sorted(t.projects()) or ['None'],
+        label='Project',
+    ),
+    'text': Field(
+        sort=lambda t: t.text().lower(),
+        group=lambda t: t.text(),
+        label='Text',
+    ),
+}
+# map UI properties to properties in the FIELDS hash
+FIELD_MAP = {
+    'completed': 'completed',
+    'completion': 'completed',
+    'completion_date': 'completed',
+    'done': 'completed',
+    'context': 'context',
+    'contexts': 'context',
+    'created': 'created',
+    'creation': 'created',
+    'creation_date': 'created',
+    'importance': 'importance',
+    'importance-avg': 'importance-avg',
+    'importance-average': 'importance-avg',
+    'length': 'length',
+    'len': 'length',
+    'prio': 'priority',
+    'priorities': 'priority',
+    'priority': 'priority',
+    'project': 'project',
+    'projects': 'project',
+    'text': 'text',
+}
+def _apply_sort_functions(p_todos, p_functions):
+    sorted_todos = p_todos
+    for function, order in reversed(p_functions):
+        sorted_todos = sorted(sorted_todos, key=function,
+                              reverse=(order == 'desc'))
+    return sorted_todos
 class Sorter(object):
@@ -93,10 +147,10 @@ class Sorter(object):
    stable.
    """
-    def __init__(self, p_sortstring="desc:priority"):
+    def __init__(self, p_sortstring="desc:priority", p_groupstring=""):
-        self.sortstring = p_sortstring
+        self.groupfunctions = self._parse(p_groupstring, p_group=True) if p_groupstring else []
-        self.functions = []
+        self.pregroupfunctions = self._parse(p_groupstring, p_group=False) if p_groupstring else []
-        self._parse()
+        self.sortfunctions = self._parse(p_sortstring, p_group=False)
    def sort(self, p_todos):
        """
@@ -107,19 +161,85 @@ class Sorter(object):
        sort operation is done first, relying on the stability of the sorted()
        function.
        """
-        sorted_todos = p_todos
+        return _apply_sort_functions(p_todos, self.sortfunctions)
-        for function, order in reversed(self.functions):
-            sorted_todos = sorted(sorted_todos, key=function,
-                                  reverse=(order == 'desc'))
-        return sorted_todos
+    def group(self, p_todos):
+        """
+        Groups the todos according to the given group string.
+        """
+        # preorder todos for the group sort
+        p_todos = _apply_sort_functions(p_todos, self.pregroupfunctions)
+        # initialize result with a single group
+        result = OrderedDict([((), p_todos)])
+        for (function, label), _ in self.groupfunctions:
+            oldresult = result
+            result = OrderedDict()
+            for oldkey, oldgroup in oldresult.items():
+                for key, _group in groupby(oldgroup, function):
+                    newgroup = list(_group)
+                    if not isinstance(key, list):
+                        key = [key]
+                    for subkey in key:
+                        subkey = "{}: {}".format(label, subkey)
+                        newkey = oldkey + (subkey,)
+                        if newkey in result:
+                            result[newkey] = result[newkey] + newgroup
+                        else:
+                            result[newkey] = newgroup
+        # sort all groups
+        for key, _group in result.items():
+            result[key] = self.sort(_group)
-    def _parse(self):
+        return result
+    def _parse(self, p_string, p_group):
        """
-        Parses a sort string and returns a list of functions and the
+        Parses a sort/group string and returns a list of functions and the
        desired order.
        """
-        fields = self.sortstring.lower().split(',')
+        def get_field_function(p_field, p_group=False):
+            """
+            Turns a field, part of a sort/group string, into a lambda that
+            takes a todo item and returns the field value.
+            """
+            compose = lambda i: i.sort if not p_group else (i.group, i.label)
+            def group_value(p_todo):
+                """
+                Returns a value to assign the given todo to a group. Date tags
+                are grouped according to the relative date (1 day, 1 month,
+                ...)
+                """
+                result = 'No value'
+                if p_todo.has_tag(p_field):
+                    if p_field == config().tag_due():
+                        result = humanize_date(p_todo.due_date())
+                    elif p_field == config().tag_start():
+                        result = humanize_date(p_todo.start_date())
+                    else:
+                        result = p_todo.tag_value(p_field)
+                return result
+            if p_field in FIELD_MAP:
+                return compose(FIELDS[FIELD_MAP[p_field]])
+            else:
+                # treat it as a tag value
+                return compose(Field(
+                    sort=lambda t: '0' + t.tag_value(p_field) if t.has_tag(p_field) else '1',
+                    group=group_value,
+                    label=p_field,
+                ))
+        result = []
+        fields = p_string.lower().split(',')
        for field in fields:
            parsed_field = re.match(
@@ -134,11 +254,14 @@ class Sorter(object):
            field = parsed_field.group('field')
            if field:
-                function = get_field_function(field)
+                function = get_field_function(field, p_group)
                # reverse order for priority: lower characters have higher
                # priority
-                if is_priority_field(field):
+                if field in FIELD_MAP and FIELD_MAP[field] == 'priority':
                    order = 'asc' if order == 'desc' else 'desc'
-                self.functions.append((function, order))
+                result.append((function, order))
+        return result
--- a/topydo/lib/TodoFile.py
+++ b/topydo/lib/TodoFile.py
@@ -19,6 +19,7 @@ This module deals with todo.txt files.
 """
 import codecs
+import os.path
 class TodoFile(object):
@@ -28,7 +29,7 @@ class TodoFile(object):
    """
    def __init__(self, p_path):
-        self.path = p_path
+        self.path = os.path.abspath(p_path)
    def read(self):
        """ Reads the todo.txt file and returns a list of todo items. """
@@ -49,6 +50,7 @@ class TodoFile(object):
        p_todos can be a list of todo items, or a string that is just written
        to the file.
        """
        todofile = codecs.open(self.path, 'w', encoding="utf-8")
        if p_todos is list:

--- a/topydo/lib/TodoFileWatched.py
+++ b/topydo/lib/TodoFileWatched.py
+# Topydo - A todo.txt client written in Python.
+# Copyright (C) 2014 - 2016 Bram Schoenmakers <bram@topydo.org>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+This module deals with todo.txt files while putting a watch on them for file
+changes.
+"""
+import os.path
+from watchdog.observers import Observer
+from watchdog.events import FileSystemEventHandler, FileModifiedEvent, FileCreatedEvent
+from topydo.lib.TodoFile import TodoFile
+class TodoFileWatched(TodoFile):
+    """
+    This class represents a todo.txt file, which can be read from or written
+    to.
+    """
+    def __init__(self, p_path, p_on_update):
+        super().__init__(p_path)
+        self.self_write = False
+        class EventHandler(FileSystemEventHandler):
+            """
+            Event handler to catch modifications (or creations) of the
+            current todo.txt file.
+            """
+            def __init__(self, p_file):
+                super().__init__()
+                self.file = p_file
+            def _handle(self, p_event):
+                right_type = isinstance(p_event, FileModifiedEvent) or isinstance(p_event, FileCreatedEvent)
+                should_trigger = right_type and p_event.src_path == self.file.path
+                if self.file.self_write and should_trigger:
+                    # the file was written by topydo, unmark that so we can
+                    # record external writes again.
+                    self.file.self_write = False
+                elif should_trigger:
+                    p_on_update()
+            def on_created(self, p_event):
+                """
+                Because vim deletes and creates a file on buffer save, also
+                catch a creation event.
+                """
+                self._handle(p_event)
+            def on_modified(self, p_event):
+                self._handle(p_event)
+        observer = Observer()
+        observer.schedule(EventHandler(self), os.path.dirname(self.path))
+        observer.start()
+    def write(self, p_todos):
+        # make sure not to reread the todo file because this instance is
+        # actually writing it
+        self.self_write = True
+        super().write(p_todos)
--- a/topydo/lib/TodoListBase.py
+++ b/topydo/lib/TodoListBase.py
@@ -24,7 +24,7 @@ from datetime import date
 from topydo.lib import Filter
 from topydo.lib.Config import config
 from topydo.lib.HashListValues import hash_list_values
-from topydo.lib.PrettyPrinter import PrettyPrinter
+from topydo.lib.printers.PrettyPrinter import PrettyPrinter
 from topydo.lib.Todo import Todo
 from topydo.lib.View import View

--- a/topydo/lib/Utils.py
+++ b/topydo/lib/Utils.py
@@ -18,6 +18,7 @@
 Various utility functions.
 """
+import arrow
 import re
 from collections import namedtuple
@@ -109,3 +110,10 @@ def translate_key_to_config(p_key):
        key = p_key
    return key
+def humanize_date(p_datetime):
+    """ Returns a relative date string from a datetime object. """
+    now = arrow.now()
+    date = now.replace(day=p_datetime.day, month=p_datetime.month, year=p_datetime.year)
+    return date.humanize(now).replace('just now', 'today')
--- a/topydo/lib/View.py
+++ b/topydo/lib/View.py
@@ -14,7 +14,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
-""" A view is a list of todos, sorted and filtered. """
+""" A view is a list of todos, sorted, grouped and filtered. """
 class View(object):
@@ -29,12 +29,22 @@ class View(object):
        self._sorter = p_sorter
        self._filters = p_filters
-    @property
+    def _apply_filters(self, p_todos):
-    def todos(self):
+        """ Applies the filters to the list of todo items. """
-        """ Returns a sorted and filtered list of todos in this view. """
+        result = p_todos
-        result = self._sorter.sort(self.todolist.todos())
        for _filter in self._filters:
            result = _filter.filter(result)
        return result
+    @property
+    def todos(self):
+        """ Returns a sorted and filtered list of todos in this view. """
+        result = self._sorter.sort(self.todolist.todos())
+        return self._apply_filters(result)
+    @property
+    def groups(self):
+        result = self._apply_filters(self.todolist.todos())
+        return self._sorter.group(result)
--- a/topydo/lib/printers/Dot.py
+++ b/topydo/lib/printers/Dot.py
+# Topydo - A todo.txt client written in Python.
+# Copyright (C) 2015 Bram Schoenmakers <me@bramschoenmakers.nl>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+Provides a printer that transforms a list of Todo items to a graph in Dot
+notation. Useful for displaying dependencies.
+"""
+from textwrap import wrap
+from topydo.lib.printers.PrettyPrinter import Printer
+from topydo.lib.ProgressColor import progress_color
+from topydo.lib.Utils import humanize_date
+class DotPrinter(Printer):
+    """
+    A printer that converts a list of Todo items to a string in Dot format.
+    """
+    def __init__(self, p_todolist):
+        super(DotPrinter, self).__init__()
+        self.todolist = p_todolist
+    def print_list(self, p_todos):
+        def node_label(p_todo):
+            """
+            Prints an HTML table for a node label with some todo details.
+            """
+            node_result = '<<TABLE CELLBORDER="0" CELLSPACING="1" VALIGN="top">'
+            def print_row(p_value1, p_value2):
+                return '<TR><TD ALIGN="RIGHT">{}</TD><TD ALIGN="LEFT">{}</TD></TR>'.format(p_value1, p_value2)
+            node_result += '<TR><TD><B>{}</B></TD><TD BALIGN="LEFT"><B>{}{}{}</B></TD></TR>'.format(
+                self.todolist.number(p_todo),
+                "<S>" if todo.is_completed() else "",
+                "<BR />".join(wrap(p_todo.text(), 35)),
+                "</S>" if todo.is_completed() else "",
+            )
+            priority = p_todo.priority()
+            start_date = p_todo.start_date()
+            due_date = p_todo.due_date()
+            if priority or start_date or due_date:
+                node_result += '<HR/>'
+            if priority:
+                node_result += print_row('Prio:', p_todo.priority())
+            if start_date:
+                node_result += print_row('Starts:', "{} ({})".format(
+                    start_date.isoformat(),
+                    humanize_date(start_date)
+                ))
+            if due_date:
+                node_result += print_row('Due:', "{} ({})".format(
+                    due_date.isoformat(),
+                    humanize_date(due_date)
+                ))
+            node_result += '</TABLE>>'
+            return node_result
+        def foreground(p_background):
+            """
+            Chooses a suitable foreground color (black or white) given a
+            background color.
+            """
+            (r, g, b) = p_background.as_rgb()
+            brightness = (r * 299 + g * 587 + b * 114) / ( 255 * 1000 )
+            return '#ffffff' if brightness < 0.5 else '#000000'
+        node_name = lambda t: '_' + str(self.todolist.number(t))
+        result = 'digraph topydo {\n'
+        result += 'node [ shape="none" margin="0" fontsize="9" fontname="Helvetica" ]\n';
+        # print todos
+        for todo in p_todos:
+            background_color = progress_color(todo)
+            result += '  {} [label={} style=filled fillcolor="{}" fontcolor="{}"]\n'.format(
+                node_name(todo),
+                node_label(todo),
+                background_color.as_html(),
+                foreground(background_color),
+            )
+        # print edges
+        for todo in p_todos:
+            # only print the children that are actually in the list of todos
+            children = set(p_todos) & set(self.todolist.children(todo,
+                p_only_direct=True))
+            for child in sorted(list(children), key=lambda t: t.text()):
+                result += '  {} -> {}\n'.format(
+                    node_name(todo),
+                    node_name(child)
+                )
+        todos_without_dependencies = [todo for todo in p_todos if not self.todolist.children(todo) and not self.todolist.parents(todo)]
+        for index in range(0, len(todos_without_dependencies) - 1):
+            this_todo = todos_without_dependencies[index]
+            next_todo = todos_without_dependencies[index + 1]
+            result += '  {} -> {} [style="invis"]\n'.format(node_name(this_todo), node_name(next_todo))
+        result += '}\n'
+        return result
--- a/topydo/lib/IcalPrinter.py
+++ b/topydo/lib/IcalPrinter.py
@@ -23,7 +23,7 @@ import random
 import string
 from datetime import datetime, time
-from topydo.lib.PrettyPrinter import Printer
+from topydo.lib.printers.PrettyPrinter import Printer
 def _convert_priority(p_priority):

--- a/topydo/lib/JsonPrinter.py
+++ b/topydo/lib/JsonPrinter.py
@@ -21,7 +21,7 @@ such that other applications can process it.
 import json
-from topydo.lib.PrettyPrinter import Printer
+from topydo.lib.printers.PrettyPrinter import Printer
 def _convert_todo(p_todo):

--- a/topydo/lib/PrettyPrinter.py
+++ b/topydo/lib/PrettyPrinter.py
@@ -14,6 +14,8 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
+from itertools import chain
 from topydo.lib.prettyprinters.Colors import PrettyPrinterColorFilter
 from topydo.lib.prettyprinters.Numbers import PrettyPrinterNumbers
 from topydo.lib.TopydoString import TopydoString
@@ -30,8 +32,16 @@ class Printer(object):
        raise NotImplementedError
    def print_list(self, p_todos):
+        result = ''
        for todo in p_todos:
-            self.print_todo(todo)
+            result += self.print_todo(todo)
+        return result
+    def print_groups(self, p_groups):
+        todos = list(chain.from_iterable(p_groups.values()))
+        return self.print_list(todos)
 class PrettyPrinter(Printer):
@@ -76,6 +86,29 @@ class PrettyPrinter(Printer):
        """
        return [self.print_todo(todo) for todo in p_todos]
+    def print_groups(self, p_groups):
+        result = []
+        first = True
+        def print_header(p_key):
+            """ Prints a header for the given key. """
+            if not first:
+                result.append('')
+            key_string = ", ".join(p_key)
+            result.append(key_string)
+            result.append("=" * len(key_string))
+        for key, todos in p_groups.items():
+            if key != ():
+                # don't print a header for the case that no valid grouping
+                # could be made (e.g. an invalid group expression)
+                print_header(key)
+            first = False
+            result += self.print_list(todos)
+        return [TopydoString(s) for s in result]
 def pretty_printer_factory(p_todolist, p_additional_filters=None):
    """ Returns a pretty printer suitable for the ls and dep subcommands. """

--- a/topydo/lib/printers/__init__.py
+++ b/topydo/lib/printers/__init__.py
--- a/topydo/ui/UILoader.py
+++ b/topydo/ui/UILoader.py
@@ -44,13 +44,13 @@ def main():
                from topydo.ui.prompt.Prompt import PromptApplication
                PromptApplication().run()
            except ImportError:
-                error("You have to install prompt-toolkit to run prompt mode.")
+                error("Some additional dependencies for prompt mode were not installed, please install with 'pip install topydo[prompt]'")
        elif args[0] == 'columns':
            try:
                from topydo.ui.columns.Main import UIApplication
                UIApplication().run()
            except ImportError:
-                error("You have to install urwid to run column mode.")
+                error("Some additional dependencies for column mode were not installed, please install with 'pip install topydo[columns]'")
        else:
            CLIApplication().run()
    except IndexError:

--- a/topydo/ui/columns/ColumnLayout.py
+++ b/topydo/ui/columns/ColumnLayout.py
@@ -15,10 +15,12 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 import configparser
+from os.path import expanduser
 from topydo.lib.Config import home_config_path, config
-def columns():
+def columns(p_alt_layout_path=None):
    """
    Returns list with complete column configuration dicts.
    """
@@ -28,6 +30,7 @@ def columns():
        column_dict['title'] = p_cp.get(p_column, 'title')
        column_dict['filterexpr'] = p_cp.get(p_column, 'filterexpr')
        column_dict['sortexpr'] = p_cp.get(p_column, 'sortexpr')
+        column_dict['groupexpr'] = p_cp.get(p_column, 'groupexpr')
        column_dict['show_all'] = p_cp.getboolean(p_column, 'show_all')
        return column_dict
@@ -36,6 +39,7 @@ def columns():
            'title':  'Yet another column',
            'filterexpr': '',
            'sortexpr': config().sort_string(),
+            'groupexpr': config().group_string(),
            'show_all': '0',
    }
@@ -49,6 +53,8 @@ def columns():
        "/etc/topydo_columns.conf",
    ]
+    if p_alt_layout_path is not None:
+        files.insert(0, expanduser(p_alt_layout_path))
    for filename in files:
        if cp.read(filename):
            break

--- a/topydo/ui/columns/Main.py
+++ b/topydo/ui/columns/Main.py
@@ -15,7 +15,9 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 import datetime
+import getopt
 import shlex
+import sys
 import time
 import urwid
@@ -28,12 +30,13 @@ from topydo.lib.Sorter import Sorter
 from topydo.lib.Filter import get_filter_list, RelevanceFilter, DependencyFilter
 from topydo.lib.Utils import get_terminal_size
 from topydo.lib.View import View
-from topydo.lib import TodoFile
+from topydo.lib.TodoFileWatched import TodoFileWatched
 from topydo.lib import TodoList
-from topydo.ui.CLIApplicationBase import CLIApplicationBase
+from topydo.ui.CLIApplicationBase import CLIApplicationBase, error
 from topydo.ui.columns.CommandLineWidget import CommandLineWidget
 from topydo.ui.columns.ConsoleWidget import ConsoleWidget
 from topydo.ui.columns.KeystateWidget import KeystateWidget
+from topydo.ui.columns.TodoWidget import TodoWidget
 from topydo.ui.columns.TodoListWidget import TodoListWidget
 from topydo.ui.columns.Utils import PaletteItem, to_urwid_color
 from topydo.ui.columns.ViewWidget import ViewWidget
@@ -91,10 +94,28 @@ class UIApplication(CLIApplicationBase):
    def __init__(self):
        super().__init__()
-        self._process_flags()
+        args = self._process_flags()
+        try:
+            opts, args = getopt.getopt(args[1:], 'l:')
+        except getopt.GetoptError as e:
+            error(str(e))
+            sys.exit(1)
+        self.alt_layout_path = None
+        for opt, value in opts:
+            if opt == "-l":
+                self.alt_layout_path = value
+        def callback():
+            self.todolist.erase()
+            self.todolist.add_list(self.todofile.read())
+            self._update_all_columns()
+            self._redraw()
        self.column_width = config().column_width()
-        self.todofile = TodoFile.TodoFile(config().todotxt())
+        self.todofile = TodoFileWatched(config().todotxt(), callback)
        self.todolist = TodoList.TodoList(self.todofile.read())
        self.marked_todos = []
@@ -172,18 +193,20 @@ class UIApplication(CLIApplicationBase):
        context_color = to_urwid_color(config().context_color())
        metadata_color = to_urwid_color(config().metadata_color())
        link_color = to_urwid_color(config().link_color())
+        focus_background_color = to_urwid_color(config().focus_background_color())
+        marked_background_color = to_urwid_color(config().marked_background_color())
        palette = [
            (PaletteItem.PROJECT, '', '', '', project_color, ''),
-            (PaletteItem.PROJECT_FOCUS, '', 'light gray', '', project_color, None),
+            (PaletteItem.PROJECT_FOCUS, '', 'light gray', '', project_color, focus_background_color),
            (PaletteItem.CONTEXT, '', '', '', context_color, ''),
-            (PaletteItem.CONTEXT_FOCUS, '', 'light gray', '', context_color, None),
+            (PaletteItem.CONTEXT_FOCUS, '', 'light gray', '', context_color, focus_background_color),
            (PaletteItem.METADATA, '', '', '', metadata_color, ''),
-            (PaletteItem.METADATA_FOCUS, '', 'light gray', '', metadata_color, None),
+            (PaletteItem.METADATA_FOCUS, '', 'light gray', '', metadata_color, focus_background_color),
            (PaletteItem.LINK, '', '', '', link_color, ''),
-            (PaletteItem.LINK_FOCUS, '', 'light gray', '', link_color, None),
+            (PaletteItem.LINK_FOCUS, '', 'light gray', '', link_color, focus_background_color),
-            (PaletteItem.DEFAULT_FOCUS, 'black', 'light gray'),
+            (PaletteItem.DEFAULT_FOCUS, '', 'light gray', '', '', focus_background_color),
-            (PaletteItem.MARKED, '', 'light blue'),
+            (PaletteItem.MARKED, '', 'light blue', '', '', marked_background_color),
        ]
        for C in ascii_uppercase:
@@ -196,7 +219,7 @@ class UIApplication(CLIApplicationBase):
                'pri_' + C, '', '', '', pri_color, ''
            ))
            palette.append((
-                'pri_' + C + '_focus', '', 'light gray', '', pri_color_focus, None
+                'pri_' + C + '_focus', '', 'light gray', '', pri_color_focus, focus_background_color
            ))
        return palette
@@ -220,6 +243,7 @@ class UIApplication(CLIApplicationBase):
    def _set_alarm_for_next_midnight_update(self):
        def callback(p_loop, p_data):
+            TodoWidget.wipe_cache()
            self._update_all_columns()
            self._set_alarm_for_next_midnight_update()
@@ -299,6 +323,8 @@ class UIApplication(CLIApplicationBase):
                              self._output if verbosity else lambda _: None)
    def _reset_state(self):
+        for widget in TodoWidget.cache.values():
+            widget.unmark()
        self.marked_todos = []
        self._update_all_columns()
@@ -389,7 +415,7 @@ class UIApplication(CLIApplicationBase):
        """
        Converts a dictionary describing a view to an actual UIView instance.
        """
-        sorter = Sorter(p_data['sortexpr'])
+        sorter = Sorter(p_data['sortexpr'], p_data['groupexpr'])
        filters = []
        if not p_data['show_all']:
@@ -535,13 +561,16 @@ class UIApplication(CLIApplicationBase):
        self._console_visible = True
        self.console.print_text(p_text)
+    def _redraw(self):
+        self.mainloop.draw_screen()
    def _input(self, p_question):
        self._print_to_console(p_question)
        # don't wait for the event loop to enter idle, there is a command
        # waiting for input right now, so already go ahead and draw the
        # question on screen.
-        self.mainloop.draw_screen()
+        self._redraw()
        user_input = self.mainloop.screen.get_input()
        self._console_visible = False
@@ -572,7 +601,7 @@ class UIApplication(CLIApplicationBase):
            return False
    def run(self):
-        layout = columns()
+        layout = columns(self.alt_layout_path)
        if len(layout) > 0:
            for column in layout:
                self._add_column(self._viewdata_to_view(column))
@@ -580,6 +609,7 @@ class UIApplication(CLIApplicationBase):
            dummy = {
                "title": "All tasks",
                "sortexpr": "desc:prio",
+                "groupexpr": "",
                "filterexpr": "",
                "show_all": True,
            }

--- a/topydo/ui/columns/TodoListWidget.py
+++ b/topydo/ui/columns/TodoListWidget.py
@@ -92,10 +92,17 @@ class TodoListWidget(urwid.LineBox):
        del self.todolist[:]
-        for todo in self.view.todos:
+        for group, todos in self.view.groups.items():
-            todowidget = TodoWidget(todo, self.view.todolist.number(todo))
+            if len(self.view.groups) > 1:
-            self.todolist.append(todowidget)
+                grouplabel = ", ".join(group)
-            self.todolist.append(urwid.Divider('-'))
+                self.todolist.append(urwid.Text(grouplabel))
+                self.todolist.append(urwid.Divider('-'))
+            for todo in todos:
+                todowidget = TodoWidget.create(todo)
+                todowidget.number = self.view.todolist.number(todo)
+                self.todolist.append(todowidget)
+                self.todolist.append(urwid.Divider('-'))
        if old_focus_position:
            try:

--- a/topydo/ui/columns/TodoWidget.py
+++ b/topydo/ui/columns/TodoWidget.py
@@ -53,7 +53,7 @@ def _markup(p_todo, p_focus):
 class TodoWidget(urwid.WidgetWrap):
-    def __init__(self, p_todo, p_number):
+    def __init__(self, p_todo):
        # clients use this to associate this widget with the given todo item
        self.todo = p_todo
@@ -87,21 +87,21 @@ class TodoWidget(urwid.WidgetWrap):
            else:
                txt_markup.append(substring)
-        id_widget = urwid.Text(str(p_number), align='right')
+        self.id_widget = urwid.Text('', align='right')
        priority_widget = urwid.Text(priority_text)
        self.text_widget = urwid.Text(txt_markup)
        progress = to_urwid_color(progress_color(p_todo)) if config().colors() else PaletteItem.DEFAULT
-        progress_bar = urwid.AttrMap(
+        self.progress_bar = urwid.AttrMap(
                urwid.SolidFill(' '),
-                urwid.AttrSpec(PaletteItem.DEFAULT, progress, 256),
+                {},
-                urwid.AttrSpec(PaletteItem.DEFAULT, progress, 256),
        )
+        self.update_progress()
        self.columns = urwid.Columns(
            [
-                (1, progress_bar),
+                (1, self.progress_bar),
-                (4, id_widget),
+                (4, self.id_widget),
                (3, priority_widget),
                ('weight', 1, self.text_widget),
            ],
@@ -128,6 +128,21 @@ class TodoWidget(urwid.WidgetWrap):
        # make sure that ListBox will highlight this widget
        return True
+    @property
+    def number(self):
+        pass
+    @number.setter
+    def number(self, p_number):
+        self.id_widget.set_text(str(p_number))
+    def update_progress(self):
+        color = to_urwid_color(progress_color(self.todo)) if config().colors() else PaletteItem.DEFAULT
+        self.progress_bar.set_attr_map(
+            {None: urwid.AttrSpec(PaletteItem.DEFAULT, color, 256)}
+        )
    def mark(self):
        attr_map = {
            None:                 PaletteItem.MARKED,
@@ -140,3 +155,45 @@ class TodoWidget(urwid.WidgetWrap):
    def unmark(self):
        self.widget.set_attr_map(_markup(self.todo, False))
+    cache = {}
+    @classmethod
+    def create(p_class, p_todo):
+        """
+        Creates a TodoWidget instance for the given todo. Widgets are
+        cached, the same object is returned for the same todo item.
+        """
+        def parent_progress_may_have_changed(p_todo):
+            """
+            Returns True when a todo's progress should be updated because it is
+            dependent on the parent's progress.
+            """
+            return p_todo.has_tag('p') and not p_todo.has_tag('due')
+        source = p_todo.source()
+        if source in p_class.cache:
+            widget = p_class.cache[source]
+            if p_todo is not widget.todo:
+                # same source text but different todo instance (could happen
+                # after an edit where a new Todo instance is created with the
+                # same text as before)
+                # simply fix the reference in the stored widget.
+                widget.todo = p_todo
+            if parent_progress_may_have_changed(p_todo):
+                widget.update_progress()
+        else:
+            widget = p_class(p_todo)
+            p_class.cache[source] = widget
+        return widget
+    @classmethod
+    def wipe_cache(p_class):
+        """ Wipes the cache """
+        p_class.cache = {}
--- a/topydo/ui/columns/ViewWidget.py
+++ b/topydo/ui/columns/ViewWidget.py
@@ -24,16 +24,18 @@ class ViewWidget(urwid.LineBox):
        self.titleedit = urwid.Edit("Title: ", "")
        self.sortedit = urwid.Edit("Sort expression: ", "")
+        self.groupedit = urwid.Edit("Group expression: ", "")
        self.filteredit = urwid.Edit("Filter expression: ", "")
-        group = []
+        radiogroup = []
-        self.relevantradio = urwid.RadioButton(group, "Only show relevant todo items", True)
+        self.relevantradio = urwid.RadioButton(radiogroup, "Only show relevant todo items", True)
-        self.allradio = urwid.RadioButton(group, "Show all todo items")
+        self.allradio = urwid.RadioButton(radiogroup, "Show all todo items")
        self.pile = urwid.Pile([
            self.filteredit,
            self.titleedit,
            self.sortedit,
+            self.groupedit,
            self.relevantradio,
            self.allradio,
            urwid.Button("Save", lambda _: urwid.emit_signal(self, 'save')),
@@ -51,6 +53,7 @@ class ViewWidget(urwid.LineBox):
        return {
            'title': self.titleedit.edit_text or self.filteredit.edit_text,
            'sortexpr': self.sortedit.edit_text or config().sort_string(),
+            'groupexpr': self.groupedit.edit_text or config().group_string(),
            'filterexpr': self.filteredit.edit_text,
            'show_all': self.allradio.state,
        }
@@ -59,6 +62,7 @@ class ViewWidget(urwid.LineBox):
    def data(self, p_data):
        self.titleedit.edit_text = p_data['title']
        self.sortedit.edit_text = p_data['sortexpr']
+        self.groupedit.edit_text = p_data['groupexpr']
        self.filteredit.edit_text = p_data['filterexpr']
        self.relevantradio.set_state(not p_data['show_all'])
        self.allradio.set_state(p_data['show_all'])

--- a/topydo/ui/prompt/Prompt.py
+++ b/topydo/ui/prompt/Prompt.py
@@ -37,21 +37,10 @@ except ConfigError as config_error:
    sys.exit(1)
 from topydo.Commands import get_subcommand
-from topydo.lib import TodoFile
+from topydo.lib.TodoFileWatched import TodoFileWatched
 from topydo.lib import TodoList
-def _todotxt_mtime():
-    """
-    Returns the mtime for the configured todo.txt file.
-    """
-    try:
-        return os.path.getmtime(config().todotxt())
-    except os.error:
-        # file not found
-        return None
 class PromptApplication(CLIApplicationBase):
    """
    This class implements a variant of topydo's CLI showing a shell and
@@ -62,33 +51,25 @@ class PromptApplication(CLIApplicationBase):
        super().__init__()
        self._process_flags()
-        self.mtime = None
        self.completer = None
+        self.todofile = TodoFileWatched(config().todotxt(), self._load_file)
    def _load_file(self):
        """
        Reads the configured todo.txt file and loads it into the todo list
        instance.
-        If the modification time of the todo.txt file is equal to the last time
-        it was checked, nothing will be done.
        """
-        current_mtime = _todotxt_mtime()
+        self.todolist.erase()
+        self.todolist.add_list(self.todofile.read())
-        if not self.todofile or self.mtime != current_mtime:
+        self.completer = TopydoCompleter(self.todolist)
-            self.todofile = TodoFile.TodoFile(config().todotxt())
-            self.todolist = TodoList.TodoList(self.todofile.read())
-            self.mtime = current_mtime
-            self.completer = TopydoCompleter(self.todolist)
    def run(self):
        """ Main entry function. """
        history = InMemoryHistory()
+        self._load_file()
        while True:
            # (re)load the todo.txt file (only if it has been modified)
-            self._load_file()
            try:
                user_input = prompt(u'topydo> ', history=history,
@@ -103,20 +84,12 @@ class PromptApplication(CLIApplicationBase):
                error('Error: ' + str(verr))
                continue
-            mtime_after = _todotxt_mtime()
            try:
                (subcommand, args) = get_subcommand(user_input)
            except ConfigError as ce:
                error('Error: ' + str(ce) + '. Check your aliases configuration')
                continue
-            # refuse to perform operations such as 'del' and 'do' if the
-            # todo.txt file has been changed in the background.
-            if subcommand and not self.is_read_only(subcommand) and self.mtime != mtime_after:
-                error("WARNING: todo.txt file was modified by another application.\nTo prevent unintended changes, this operation was not executed.")
-                continue
            try:
                if self._execute(subcommand, args) != False:
                    self._post_execute()

--- a/topydo_columns.conf
+++ b/topydo_columns.conf
 [all]
 title = All tasks
 filterexpr = 
+groupexpr = 
 [today]
 title = Due today