python-etk.docking 0.2-1 / usr / share / pyshared / etk / docking / dockgroup.py

# -*- coding: utf-8 -*-
# vim:sw=4:et:ai

# Copyright © 2010 etk.docking Contributors
#
# This file is part of etk.docking.
#
# etk.docking is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# etk.docking 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with etk.docking. If not, see <http://www.gnu.org/licenses/>.


from __future__ import absolute_import
from logging import getLogger
from math import pi
from operator import attrgetter
from time import time

import cairo
import gobject
import gtk
import gtk.gdk as gdk

from . import _
from .compactbutton import CompactButton
from .dockitem import DockItem
from .dnd import DockDragContext, DRAG_TARGET_ITEM_LIST
from .hslcolor import HslColor
from .util import rect_contains


class _DockGroupTab(object):
    '''
    Convenience class storing information about a tab.
    '''
    __slots__ = ['item',                # DockItem associated with this tab
                 'item_title_handler',  # item title property notification signal handler id
                 'item_title_tooltip_text_handler',
                                        # item title-tooltip-text property notification signal handler id
                 'image',               # icon (gtk.Image)
                 'label',               # title (gtk.Label)
                 'button',              # close button (etk.docking.CompactButton)
                 'menu_item',           # menu item (gtk.ImageMenuItem)
                 'area',                # area, used for hit testing (gdk.Rectangle)
                 'last_focused']        # timestamp set last time a tab was focused

    def __contains__(self, pos):
        return rect_contains(self.area, *pos)

    def __str__(self):
        return "<%s object at 0x%s with label '%s' on %s>" % (self.__class__.__name__,
                                                              hex(id(self)),
                                                              self.item.get_title(),
                                                              self.area)


class DockGroup(gtk.Container):
    '''
    The etk.DockGroup widget is a gtk.Container that groups its children in a
    tabbed interface.

    Tabs can be reorder by dragging them to the desired location within the
    same or another etk.DockGroup having the same group-id. You can also drag
    a complete etk.DockGroup onto another etk.DockGroup having the same group-id
    to merge all etk.DockItems from the source into the destination
    etk.DockGroup.
    '''
    __gtype_name__ = 'EtkDockGroup'
    __gsignals__ = {'item-added':
                        (gobject.SIGNAL_RUN_LAST,
                         gobject.TYPE_NONE,
                         (gobject.TYPE_OBJECT,)),
                    'item-removed':
                        (gobject.SIGNAL_RUN_LAST,
                         gobject.TYPE_NONE,
                         (gobject.TYPE_OBJECT,)),
                    'item-selected':
                        (gobject.SIGNAL_RUN_LAST,
                         gobject.TYPE_NONE,
                         (gobject.TYPE_OBJECT,))}

    def __init__(self):
        gtk.Container.__init__(self)

        # Initialize logging
        self.log = getLogger('%s.%s' % (self.__gtype_name__, hex(id(self))))

        # Internal housekeeping
        self.set_border_width(2)
        self._frame_width = 1
        self._spacing = 3
        self._available_width = 0
        self._decoration_area = gdk.Rectangle()

        self._tabs = []
        self._visible_tabs = []
        self._current_tab = None
        self._tab_state = gtk.STATE_SELECTED
        self.dragcontext = DockDragContext()

        gtk.widget_push_composite_child()
        self._list_button = CompactButton('compact-list')
        self._list_button.set_tooltip_text(_('Show list'))
        self._list_button.connect('clicked', self._on_list_button_clicked)
        self._list_button.set_parent(self)
        self._min_button = CompactButton('compact-minimize')
        self._min_button.set_tooltip_text(_('Minimize'))
        self._min_button.connect('clicked', self._on_min_button_clicked)
        self._min_button.set_parent(self)
        self._max_button = CompactButton('compact-maximize')
        self._max_button.set_tooltip_text(_('Maximize'))
        self._max_button.connect('clicked', self._on_max_button_clicked)
        self._max_button.set_parent(self)
        self._tab_menu = gtk.Menu()
        self._tab_menu.attach_to_widget(self, None)
        self._list_menu = gtk.Menu()
        self._list_menu.attach_to_widget(self._list_button, None)
        gtk.widget_pop_composite_child()

    def __len__(self):
        return len(self._tabs)

    ############################################################################
    # GtkWidget
    ############################################################################
    def do_realize(self):
        # Internal housekeeping
        self.set_flags(self.flags() | gtk.REALIZED)
        self.window = gdk.Window(self.get_parent_window(),
                                 x = self.allocation.x,
                                 y = self.allocation.y,
                                 width = self.allocation.width,
                                 height = self.allocation.height,
                                 window_type = gdk.WINDOW_CHILD,
                                 wclass = gdk.INPUT_OUTPUT,
                                 event_mask = (gdk.EXPOSURE_MASK |
                                               gdk.POINTER_MOTION_MASK |
                                               gdk.BUTTON_PRESS_MASK |
                                               gdk.BUTTON_RELEASE_MASK))
        self.window.set_user_data(self)
        self.style.attach(self.window)
        self.style.set_background(self.window, gtk.STATE_NORMAL)

        # Set parent window on all child widgets
        for tab in self._tabs:
            tab.image.set_parent_window(self.window)
            tab.label.set_parent_window(self.window)
            tab.button.set_parent_window(self.window)
            tab.item.set_parent_window(self.window)

        self._list_button.set_parent_window(self.window)
        self._min_button.set_parent_window(self.window)
        self._max_button.set_parent_window(self.window)

    def do_unrealize(self):
        self.window.set_user_data(None)
        self.window.destroy()
        gtk.Container.do_unrealize(self)

    def do_map(self):
        gtk.Container.do_map(self)
        self._list_button.show()
        self._min_button.show()
        self._max_button.show()
        self.window.show()

    def do_unmap(self):
        self._list_button.hide()
        self._min_button.hide()
        self._max_button.hide()
        self.window.hide()
        gtk.Container.do_unmap(self)

    def do_size_request(self, requisition):
        gtk.Container.do_size_request(self, requisition)

        # Start with a zero sized decoration area
        dw = dh = 0

        # Compute width and height for each tab, but only add
        # current item tab size to the decoration area requisition as
        # the other tabs can be hidden when we don't get enough room
        # in the allocation fase.
        for tab in self._tabs:
            (iw, ih) = tab.image.size_request()
            (lw, lh) = tab.label.size_request()
            (bw, bh) = tab.button.size_request()

            tab.area.width = (self._frame_width + self._spacing +
                              iw + self._spacing + lw + self._spacing +
                              bw + self._spacing + self._frame_width)
            tab.area.height = (self._frame_width + self._spacing +
                               max(ih, lh, bh) +
                               self._spacing + self._frame_width)

            if tab == self._current_tab:
                dw = tab.area.width - lw

            dh = max(dh, tab.area.height)

        # Add decoration button sizes to the decoration area
        (list_w, list_h) = self._list_button.size_request()
        (min_w, min_h) = self._min_button.size_request()
        (max_w, max_h) = self._max_button.size_request()

        dw += (self._spacing + list_w + min_w + max_w +
               self._spacing + self._frame_width)
        dh = max(dh,
                 (self._spacing + list_h + self._spacing),
                 (self._spacing + min_h + self._spacing),
                 (self._spacing + max_h + self._spacing))

        # Store decoration area size for later usage
        self._decoration_area.width = dw
        self._decoration_area.height = dh

        # Current item: we only honor the height request
        if self._current_tab:
            ih = self._current_tab.item.size_request()[1]
        else:
            ih = 0

        ih += self._frame_width + 2 * self.border_width

        # Compute total size requisition
        requisition.width = dw
        requisition.height = dh + ih

    def do_size_allocate(self, allocation):
        self.allocation = allocation

        if self.flags() & gtk.REALIZED:
            self.window.move_resize(*allocation)

        # Allocate space for decoration buttons
        max_w, max_h = self._max_button.get_child_requisition()
        min_w, min_h = self._min_button.get_child_requisition()
        list_w, list_h = self._list_button.get_child_requisition()
        bh = max(list_h, min_h, max_h)
        by = self._frame_width + self._spacing
        self._max_button.size_allocate(gdk.Rectangle(allocation.width - self._frame_width - self._spacing - max_w, by, max_w, bh))
        self._min_button.size_allocate(gdk.Rectangle(allocation.width - self._frame_width - self._spacing - max_w - min_w, by, min_w, bh))
        self._list_button.size_allocate(gdk.Rectangle(allocation.width - self._frame_width - self._spacing - max_w - min_w - list_w, by, list_w, bh))

        # Compute available tab area width
        self._available_width = (allocation.width - self._frame_width - self._spacing - max_w - min_w - list_w - self._spacing)

        # Update visible tabs
        self._update_visible_tabs()

        # Update visibility on dockitems and composite children used by tabs.
        for tab in self._tabs:
            if tab is self._current_tab:
                tab.item.show()
                tab.image.show()
                tab.label.show()
                tab.button.show()
            elif tab in self._visible_tabs:
                tab.item.hide()
                tab.image.show()
                tab.label.show()
            elif tab.item.flags() & gtk.VISIBLE:
                tab.item.hide()
                tab.image.hide()
                tab.label.hide()
                tab.button.hide()

        # Only show the list button when needed
        if len(self._tabs) > len(self._visible_tabs):
            self._list_button.show()
        else:
            self._list_button.hide()

        # Compute x an y for each visible tab and allocate space for
        # the tab's composite children.
        cx = cy = 0

        for tab in self._visible_tabs:
            tab.area.x = cx
            tab.area.y = cy

            (iw, ih) = tab.image.get_child_requisition()
            (lw, lh) = tab.label.get_child_requisition()
            (bh, bw) = tab.button.get_child_requisition()

            ix = cx + self._frame_width + self._spacing
            iy = (tab.area.height - ih) / 2 + 1
            tab.image.size_allocate(gdk.Rectangle(ix, iy, iw, ih))

            if len(self._visible_tabs) == 1:
                lw = tab.area.width - (self._frame_width + self._spacing + iw +
                                       self._spacing + self._spacing + bw +
                                       self._spacing + self._frame_width)
                lw = max(lw, 0) # Prevent negative width

            lx = cx + self._frame_width + self._spacing + iw + self._spacing
            ly = (tab.area.height - lh) / 2 + 1
            tab.label.size_allocate(gdk.Rectangle(lx, ly, lw, lh))

            bx = (cx + self._frame_width + self._spacing + iw +
                  self._spacing + lw + self._spacing)
            by = (tab.area.height - bh) / 2 + 1
            tab.button.size_allocate(gdk.Rectangle(bx, by, bw, bh))

            cx += tab.area.width

        # Allocate space for the current *item*
        if self._current_tab:
            ix = self._frame_width + self.border_width
            iy = self._decoration_area.height + self.border_width
            iw = max(allocation.width - (2 * self._frame_width) - (2 * self.border_width), 0)
            ih = max(allocation.height - (2 * self._frame_width) - (2 * self.border_width) - 23, 0)
            self._current_tab.item.size_allocate(gdk.Rectangle(ix, iy, iw, ih))

        #assert not self._current_tab or self._current_tab in self._visible_tabs
        self.queue_draw_area(0, 0, self.allocation.width, self.allocation.height)

    def do_expose_event(self, event):
        # Prepare colors
        bg = self.style.bg[self.state]
        bg = (bg.red_float, bg.green_float, bg.blue_float)
        dark = self.style.dark[self.state]
        dark = (dark.red_float, dark.green_float, dark.blue_float)
        tab_light = self.style.text_aa[self._tab_state]
        tab_light = (tab_light.red_float, tab_light.green_float, tab_light.blue_float)
        tab_dark = HslColor(self.style.text_aa[gtk.STATE_SELECTED])
        tab_dark.set_l(0.9)
        tab_dark = tab_dark.get_rgb_float()

        # Create cairo context
        c = self.window.cairo_create()

        # Restrict context to the exposed area, avoid extra work
        c.rectangle(event.area.x, event.area.y, event.area.width, event.area.height)
        c.clip_preserve()

        # Draw background
        c.set_source_rgb(*bg)
        c.fill()

        # Draw frame
        a = self.allocation
        c.set_line_width(self._frame_width)
        c.rectangle(0.5, 0.5, a.width - 1, a.height - 1)
        c.set_source_rgb(*dark)
        c.stroke()
        c.move_to(0.5, self._decoration_area.height - 0.5)
        c.line_to(a.width + 0.5, self._decoration_area.height - 0.5)
        c.set_source_rgb(*dark)
        c.stroke()

        if self._visible_tabs:
            # Draw border
            c.set_line_width(self.border_width)
            c.rectangle(self._frame_width + self.border_width / 2,
                        self._decoration_area.height + self.border_width / 2,
                        a.width - (2 * self._frame_width) - self.border_width,
                        a.height - self._decoration_area.height - self._frame_width - self.border_width)
            c.set_source_rgb(*tab_light)
            c.stroke()

            # Draw tabs
            c.set_line_width(self._frame_width)

            try:
                # Fails if expose event happens before size request/allocate when a new
                # current_tab has been selected.
                visible_index = self._visible_tabs.index(self._current_tab)
            except ValueError:
                visible_index = -1

            for index, tab in enumerate(self._visible_tabs):
                tx = tab.area.x
                ty = tab.area.y
                tw = tab.area.width
                th = tab.area.height

                if index < visible_index and index != 0:
                    c.move_to(tx + 0.5, ty + th)
                    c.line_to(tx + 0.5, ty + 8.5)
                    c.arc(tx + 8.5, 8.5, 8, 180 * (pi / 180), 270 * (pi / 180))
                    c.set_source_rgb(*dark)
                    c.stroke()
                elif index > visible_index:
                    c.arc(tx + tw - 8.5, 8.5, 8, 270 * (pi / 180), 360 * (pi / 180))
                    c.line_to(tx + tw - 0.5, ty + th)
                    c.set_source_rgb(*dark)
                    c.stroke()
                elif index == visible_index:
                    c.move_to(tx + 0.5, ty + th)

                    if visible_index == 0:
                        c.line_to(tx + 0.5, ty + 0.5)
                        c.line_to(tx + tw - 8.5, ty + 0.5)
                    else:
                        c.line_to(tx + 0.5, ty + 8.5)
                        c.arc(tx + 8.5, 8.5, 8, 180 * (pi / 180), 270 * (pi / 180))
                        c.line_to(tx + tw - 8.5, ty + 0.5)

                    c.arc(tx + tw - 8.5, 8.5, 8, 270 * (pi / 180), 360 * (pi / 180))
                    c.line_to(tx + tw - 0.5, ty + th)
                    linear = cairo.LinearGradient(0.5, 0.5, 0.5, th)
                    linear.add_color_stop_rgb(1, *tab_light)
                    linear.add_color_stop_rgb(0, *tab_dark)
                    c.set_source(linear)
                    c.fill_preserve()
                    c.set_source_rgb(*dark)
                    c.stroke()

                    self.propagate_expose(self._current_tab.item, event)

                self.propagate_expose(tab.image, event)
                self.propagate_expose(tab.label, event)
                self.propagate_expose(tab.button, event)

        self.propagate_expose(self._list_button, event)
        self.propagate_expose(self._min_button, event)
        self.propagate_expose(self._max_button, event)

        return False

    def do_button_press_event(self, event):
        '''
        :param event: the event that triggered the signal
        :returns: True to stop other handlers from being invoked for the event.
                  False to propagate the event further.

        The do_button_press_event() signal handler is executed when a mouse
        button is pressed.
        '''

        # We might start a DnD operation, or we could simply be starting
        # a click on a tab. Store information from this event in self.dragcontext
        # and decide in do_motion_notify_event if we're actually starting a
        # dnd operation.
        if event.window is self.window and event.button == 1:
            self.dragcontext.source_x = event.x
            self.dragcontext.source_y = event.y
            self.dragcontext.source_button = event.button

        return True

    def do_button_release_event(self, event):
        '''
        :param event: the event that triggered the signal
        :returns: True to stop other handlers from being invoked for the event.
                  False to propagate the event further.

        The do_button_release_event() signal handler is executed when a mouse
        button is released.
        '''

        # Did we click a tab?
        clicked_tab = self.get_tab_at_pos(event.x, event.y)

        if clicked_tab:
            # Set the current item on left click
            if event.button == 1:
                self.set_current_item(self._tabs.index(clicked_tab))
            # Show context menu on right click
            elif event.button == 3:
                #TODO: implement tab context menu
                def _menu_position(menu):
                    wx, wy = self.window.get_origin()
                    x = int(wx + event.x)
                    y = int(wy + event.y)
                    return (x, y, True)

                self._tab_menu.show_all()
                self._tab_menu.popup(parent_menu_shell=None,
                                     parent_menu_item=None,
                                     func=_menu_position,
                                     button=event.button,
                                     activate_time=event.time)

        return True

    def do_motion_notify_event(self, event):
        '''
        :param event: the event that triggered the signal
        :returns: True to stop other handlers from being invoked for the event.
                  False to propagate the event further.

        The do_motion-notify-event() signal handler is executed when the mouse
        pointer moves while over this widget.
        '''

        # Reset tooltip text
        self.set_tooltip_text(None)

        # We should not react to motion_notify_events originating from the
        # current tab's child widget
        if event.window is self.window:
            # Check if we are actually starting a DnD operation
            if event.state & gdk.BUTTON1_MASK and \
               self.dragcontext.source_button == 1 and \
               self.drag_check_threshold(int(self.dragcontext.source_x),
                                         int(self.dragcontext.source_y),
                                         int(event.x), int(event.y)):
                self.log.debug('drag_begin')
                self.dragcontext.dragging = True

                # What are we dragging?
                tab = self.get_tab_at_pos(self.dragcontext.source_x,
                                          self.dragcontext.source_y)

                if tab:
                    self.dragcontext.dragged_object = [tab.item]
                else:
                    self.dragcontext.dragged_object = [t.item for t in self._tabs]

                if self.dragcontext.dragged_object:
                    self.drag_begin([DRAG_TARGET_ITEM_LIST], gdk.ACTION_MOVE,
                                    self.dragcontext.source_button, event)

            # Update tab button visibility
            for tab in self._visible_tabs:
                if (event.x, event.y) in tab:
                    # Update tooltip for tab under the cursor
                    self.set_tooltip_text(tab.item.get_title_tooltip_text())

                    tab.button.show()
                else:
                    tab.button.hide()

        return True

    ############################################################################
    # GtkWidget drag source
    ############################################################################
    def do_drag_begin(self, context):
        '''
        :param context: the gdk.DragContext

        The do_drag_begin() signal handler is executed on the drag source when
        the user initiates a drag operation. A typical reason to use this signal
        handler is to set up a custom drag icon with the drag_source_set_icon()
        method.
        '''
        # Free the item for transport.
        for item in self.dragcontext.dragged_object:
            self._dragged_tab_index = [t.item for t in self._tabs].index(item)
            self.remove_item(self._dragged_tab_index)

        #TODO: Set drag icon to be empty
        #TODO: Set drag cursor -> will most likely not (only) happen here...
        # Can be any of the following, depending on the selected drag destination:
        #   - gdk.DIAMOND_CROSS    "stacking" a dockitem into a dockgroup
        #   - gdk.SB_UP_ARROW      "splitting" a dockitem into a new dockgroup above the source dockgroup (needs docklayout)
        #   - gdk.SB_DOWN_ARROW    "splitting" a dockitem into a new dockgroup below the source dockgroup (needs docklayout)
        #   - gdk.SB_LEFT_ARROW    "splitting" a dockitem into a new dockgroup on the left of the source dockgroup (needs docklayout)
        #   - gdk.SB_RIGHT_ARROW   "splitting" a dockitem into a new dockgroup on the right of the source dockgroup (needs docklayout)

        #dnd_window = gtk.Window(gtk.WINDOW_POPUP)
        #dnd_window.set_screen(self.get_screen())
        #dnd_window.add(tab.item)
        #dnd_window.set_size_request(tab.item.allocation.width,
        #                            tab.item.allocation.height)
        #dnd_window.show_all()
        #context.set_icon_widget(dnd_window, -2, -2)
        #context.set_icon_pixmap(tab.image.get_pixmap(), -2, -2)

    def do_drag_data_get(self, context, selection_data, info, timestamp):
        '''
        :param context: the gdk.DragContext
        :param selection_data: a gtk.SelectionData object
        :param info: an integer ID for the drag
        :param timestamp: the time of the drag event

        The do_drag_data_get() signal handler is executed when a drag operation
        completes that copies data or when a drag drop occurs using the
        gdk.DRAG_PROTO_ROOTWIN protocol. The drag source executes this
        handler when the drag destination requests the data using the
        drag_get_data() method. This handler needs to fill selection_data
        with the data in the format specified by the target associated with
        info.

        For tab movement, here the tab is removed from the group. If the
        drop fails, the tab is restored in do_drag_failed().

        For group movement, no special action is taken.
        '''
        # Set some data so the DnD process continues
        selection_data.set(gdk.atom_intern(DRAG_TARGET_ITEM_LIST[0]),
                           8,
                           '%d tabs' % len(self.dragcontext.dragged_object))

    def do_drag_data_delete(self, context):
        '''
        :param context: the gdk.DragContext

        The do_drag_data_delete() signal handler is executed when the drag
        completes a move operation and requires the source data to be deleted.
        The handler is responsible for deleting the data that has been dropped.

        For groups, the group is deleted, for tabs the group is destroyed
        of there are no more tabs left (see do_drag_data_get()).
        '''
        # Let this be handled by the DockLayout
        pass

    def do_drag_end(self, context):
        '''
        :param context: the gdk.DragContext

        The do_drag_end() signal handler is executed when the drag operation is
        completed. A typical reason to use this signal handler is to undo things
        done in the do_drag_begin() handler.

        In this case, items distached on drag-begin are connected to the group
        again, if not attached to some other widget already.
        '''
        if self.dragcontext.dragging and self.dragcontext.dragged_object:
            for item in self.dragcontext.dragged_object:
                if not item.get_parent():
                    self.insert_item(item)

        self.dragcontext.reset()
        self.queue_resize()

    ############################################################################
    # GtkContainer
    ############################################################################
    def do_forall(self, internals, callback, data):
        # Internal widgets
        if internals:
            for tab in self._tabs:
                callback(tab.image, data)
                callback(tab.label, data)
                callback(tab.button, data)

            callback(self._list_button, data)
            callback(self._min_button, data)
            callback(self._max_button, data)

        # Docked items
        for tab in self._tabs:
            callback(tab.item, data)

    def do_add(self, widget):
        if widget not in (tab.item for tab in self._tabs):
            self._insert_item(widget)

    def do_remove(self, widget):
        self._remove_item(widget)

    def _remove_item(self, child):
        assert child in (tab.item for tab in self._tabs)

        item_num = self.item_num(child)
        tab = self._tabs[item_num]

        # We need this to reset the current item below
        old_tab_index = self._tabs.index(self._current_tab)

        # Remove tab item
        tab.item.disconnect(tab.item_title_handler)
        tab.item.disconnect(tab.item_title_tooltip_text_handler)
        tab.item.unparent()

        # Remove child widgets
        tab.image.unparent()
        tab.image.destroy()
        tab.label.unparent()
        tab.label.destroy()
        tab.button.unparent()
        tab.button.destroy()
        self._list_menu.remove(tab.menu_item)
        tab.menu_item.destroy()
        self._tabs.remove(tab)

        # Refresh ourselves
        current_tab_index = old_tab_index

        if item_num < current_tab_index:
            item_num = current_tab_index - 1

        self.set_current_item(item_num)
        self.emit('item-removed', child)

    ############################################################################
    # EtkDockGroup
    ############################################################################
    items = property(lambda s: [t.item for t in s._tabs])

    visible_items = property(lambda s: [t.item for t in s._visible_tabs])

    def __contains__(self, item):
        return item in self.items

    def _update_visible_tabs(self):
        # Check what tabs we can show with the space we have been allocated.
        # Tabs on the far right of the current item tab get hidden first,
        # then tabs on the far left.
        if not self._tabs:
            del self._visible_tabs[:]
        else:
            # TODO: get previous tab position, use that to insert _current_tab
            if self._current_tab and self._current_tab not in self._visible_tabs:
                self._visible_tabs.append(self._current_tab)

            #if not set(self._visible_tabs) <= set(self._tabs):
            for tab in self._visible_tabs:
                if tab not in self._tabs:
                    self._visible_tabs.remove(tab)

                # TODO: There are other places where something like this happens,
                #       notably do_motion_notify_event. Consider some cleanup...
                if tab is self._current_tab:
                    tab.button.show()
                else:
                    tab.button.hide()

            available_width = self._available_width
            calculated_width = 0

            for tab in self._visible_tabs:
                calculated_width += tab.area.width

            if calculated_width < available_width and len(self._visible_tabs) < len(self._tabs):
                tab_age = sorted(self._tabs, key=attrgetter('last_focused'), reverse=True)

                while tab_age and calculated_width < available_width:
                    if tab_age[0] not in self._visible_tabs:
                        calculated_width += tab_age[0].area.width
                        self._visible_tabs.append(tab_age[0])

                    del tab_age[0]

            if calculated_width > available_width:
                tab_age = sorted(self._visible_tabs, key=attrgetter('last_focused'))

                while len(tab_age) > 1 and calculated_width > available_width:
                    calculated_width -= tab_age[0].area.width
                    self._visible_tabs.remove(tab_age[0])
                    del tab_age[0]

            # If the current item's tab is the only visible tab,
            # we need to recalculate its tab.area.width
            if len(self._visible_tabs) == 1:
                (iw, ih) = self._current_tab.image.get_child_requisition()
                (lw, lh) = self._current_tab.label.get_child_requisition()
                (bh, bw) = self._current_tab.button.get_child_requisition()

                normal = (self._frame_width + self._spacing + iw +
                          self._spacing + lw + self._spacing + bw +
                          self._spacing + self._frame_width)

                if available_width <= normal:
                    self._current_tab.area.width = available_width
                else:
                    self._current_tab.area.width = normal

    def set_tab_state(self, tab_state):
        '''
        Define the tab state. Normally that will be ``gtk.STATE_SELECTED``, but a
        different state can be set if required.
        '''
        self._tab_state = tab_state

        if self.allocation:
            self.queue_draw_area(0, 0, self.allocation.width, self.allocation.height)

    def get_tab_state(self):
        '''
        Current state for drawing tabs.
        '''
        return self._tab_state

    def get_tab_at_pos(self, x, y):
        '''
        :param x: the x coordinate of the position
        :param y: the y coordinate of the position
        :returns: the item tab at the position specified by x and y or None

        The get_tab_at_pos() method returns the _DockGroupTab whose area
        contains the position specified by x and y or None if no _DockGroupTab
        area contains position.
        '''
        for tab in self._visible_tabs:
            if (x, y) in tab:
                return tab
        else:
            return None

    def append_item(self, item):
        '''
        :param item: a DockItem
        :returns: the index number of the item tab in the DockGroup

        The append_item() method appends a DockItem to the DockGroup using the
        DockItem specified by item.
        '''
        return self.insert_item(item)

    def prepend_item(self, item):
        '''
        :param item: a DockItem
        :returns: the index number of the item tab in the DockGroup

        The prepend_item() method prepends a DockItem to the DockGroup using the
        DockItem specified by item.
        '''
        return self.insert_item(item, position=0)

    def insert_item(self, item, position=None, visible_position=None):
        '''
        :param item: a DockItem
        :param position: the index (starting at 0) at which to insert the item,
                         or None to append the item after all other item tabs.
        :param visible_position: the index at which the newly inserted item should
                         be displayed. This index is usually different from the
                         position and is normally only used when dropping items on
                         the group.
        :returns: the index number of the item tab in the DockGroup

        The insert_item() method inserts a DockItem into the DockGroup at the
        location specified by position (0 is the first item). item is the
        DockItem to insert. If position is None the item is appended to the
        DockGroup.
        '''
        index = self._insert_item(item, position, visible_position)
        return index

    def _insert_item(self, item, position=None, visible_position=None):
        assert isinstance(item, DockItem)
        assert self.item_num(item) is None

        if position is None or position < 0:
            position = len(self)

        # Create composite children for tab
        gtk.widget_push_composite_child()
        tab = _DockGroupTab()
        tab.image = item.get_image()
        tab.label = gtk.Label()
        tab.button = CompactButton(has_frame=False)
        tab.menu_item = gtk.ImageMenuItem()
        gtk.widget_pop_composite_child()

        # Configure child widgets for tab
        tab.item = item
        tab.item.set_parent(self)
        tab.item_title_handler = tab.item.connect('notify::title', self._on_item_title_changed, tab)
        tab.item_title_tooltip_text_handler = tab.item.connect('notify::title-tooltip-text', self._on_item_title_tooltip_text_changed, tab)
        tab.image.set_parent(self)
        tab.label.set_text(item.get_title())
        tab.label.set_parent(self)
        tab.button.set_icon_name_normal('compact-close')
        tab.button.set_icon_name_prelight('compact-close-prelight')
        tab.button.set_parent(self)
        tab.button.connect('clicked', self._on_tab_button_clicked, item)
        tab.menu_item.set_image(item.get_image())
        tab.menu_item.set_label(item.get_title())
        tab.menu_item.connect('activate', self._on_list_menu_item_activated, tab)
        self._list_menu.append(tab.menu_item)
        tab.area = gdk.Rectangle()
        tab.last_focused = time()

        if self.flags() & gtk.REALIZED:
            tab.item.set_parent_window(self.window)
            tab.image.set_parent_window(self.window)
            tab.label.set_parent_window(self.window)
            tab.button.set_parent_window(self.window)

        self._tabs.insert(position, tab)
        self.emit('item-added', item)

        #TODO: get rid of this pronto!
        if visible_position is not None:
            self._visible_tabs.insert(visible_position, tab)

        item_num = self.item_num(item)
        self.set_current_item(item_num)

        return item_num

    def remove_item(self, item_num):
        '''
        :param item_num: the index of an item tab, starting from 0. If None,
                         the last item will be removed.

        The remove_item() method removes the item at the location specified by
        item_num. The value of item_num starts from 0.
        '''
        if item_num is None:
            tab = self._tabs[-1]
        else:
            tab = self._tabs[item_num]
        item = tab.item

        self._remove_item(item)

    def item_num(self, item):
        '''
        :param item: a DockItem
        :returns: the index of the item tab specified by item, or None if item
                  is not in the DockGroup

        The item_num() method returns the index of the item tab which contains
        the DockItem specified by item or None if no item tab contains item.
        '''
        for tab in self._tabs:
            if tab.item is item:
                return self._tabs.index(tab)
        return None

    def get_n_items(self):
        '''
        :returns: the number of item tabs in the DockGroup.

        The get_n_items() method returns the number of item tabs in the
        DockGroup.
        '''
        return len(self)

    def get_nth_item(self, item_num):
        '''
        :param item_num: the index of an item tab in the DockGroup.
        :returns: a DockItem, or None if item_num is out of bounds.

        The get_nth_item() method returns the DockItem contained in the item tab
        with the index specified by item_num. If item_num is out of bounds for
        the item range of the DockGroup this method returns None.
        '''
        if item_num >= 0 and item_num <= len(self._tabs) - 1:
            return self._tabs[item_num].item
        else:
            return None

    def get_current_item(self):
        '''
        :returns: the index (starting from 0) of the current item tab in the
                  DockGroup. If the DockGroup has no item tabs, then None will
                  be returned.

        The get_current_item() method returns the index of the current item tab
        numbered from 0, or None if there are no item tabs.
        '''
        if self._current_tab:
            return self._tabs.index(self._current_tab)
        else:
            return None

    def set_current_item(self, item_num):
        '''
        :param item_num: the index of the item tab to switch to, starting from
                         0. If negative, the first item tab will be used. If
                         greater than the number of item tabs in the DockGroup,
                         the last item tab will be used.

        Switches to the item number specified by item_num. If item_num is
        negative the first item is selected. If greater than the number of
        items in the DockGroup, the last item is selected.
        '''
        # Store a reference to the old current tab
        if self._current_tab and self._current_tab in self._tabs:
            old_tab = self._current_tab
        else:
            old_tab = None

        # Switch to the new current tab
        if self._tabs:
            if item_num < 0:
                current_tab_index = 0
            elif item_num > len(self._tabs) - 1:
                current_tab_index = len(self._tabs) - 1
            else:
                current_tab_index = item_num

            self._current_tab = self._tabs[current_tab_index]
            self._current_tab.last_focused = time()
            # Update properties on new current tab
            self._item_title_changed(self._current_tab)
            self._on_item_title_tooltip_text_changed(self._current_tab)
            self.emit('item-selected', self._current_tab.item)
        else:
            self._current_tab = None

        # Update properties on old current tab
        if old_tab:
            self._item_title_changed(old_tab)
            self._on_item_title_tooltip_text_changed(old_tab)

        # Refresh ourselves
        self.queue_resize()

    def next_item(self):
        '''
        The next_item() method switches to the next item. Nothing happens if
        the current item is the last item.
        '''
        ci = self.get_current_item()

        if not ci == len(self) - 1:
            self.set_current_item(ci + 1)

    def prev_item(self):
        '''
        The prev_item() method switches to the previous item. Nothing happens
        if the current item is the first item.
        '''
        ci = self.get_current_item()

        if not ci == 0:
            self.set_current_item(ci - 1)

    def reorder_item(self, item, position):
        '''
        :param item: the DockItem widget to move
        :param position: the index of the item tab that item is to move to

        The reorder_item() method reorders the DockGroup items so that item
        appears in the location specified by position. If position is greater
        than or equal to the number of children in the list, item will be moved
        to the end of the list. If position is negative, item will be moved
        to the beginning of the list.
        '''
        assert self.item_num(item) is not None

        if position < 0:
            position = 0
        elif position > len(self) - 1:
            position = len(self)

        tab = self._tabs[self.item_num(item)]
        self._tabs.remove(tab)
        self._tabs.insert(position, tab)

    ############################################################################
    # Property notification signal handlers
    ############################################################################
    def _item_title_changed(self, tab):
        tab.label.set_text(tab.item.get_title())
        self.queue_resize()

        if tab is self._current_tab:
            tab.menu_item.child.set_use_markup(True)
            tab.menu_item.child.set_markup('<b>%s</b>' % tab.item.get_title())
        else:
            tab.menu_item.child.set_use_markup(False)
            tab.menu_item.child.set_markup(tab.item.get_title())

    def _on_item_title_changed(self, item, pspec, tab):
        self._item_title_changed(tab)

    def _on_item_title_tooltip_text_changed(self, tab):
        tab.menu_item.set_tooltip_text(tab.item.get_title_tooltip_text())

    ############################################################################
    # Decoration area signal handlers
    ############################################################################
    def _on_tab_button_clicked(self, button, item):
        item.close()

    def _on_list_button_clicked(self, button):
        def _menu_position(menu):
            wx, wy = self.window.get_origin()
            x = wx + button.allocation.x
            y = wy + button.allocation.y + button.allocation.height
            return (x, y, True)

        self._list_menu.show_all()
        self._list_menu.popup(parent_menu_shell=None, parent_menu_item=None,
                              func=_menu_position, button=1,
                              activate_time=0)

    def _on_list_menu_item_activated(self, menuitem, tab):
        self.set_current_item(self._tabs.index(tab))

    def _on_min_button_clicked(self, button):
        #TODO: Hiding the dockgroup is not a good idea, as it will be 'minimized'
        # into a toolbar, managed by DockLayout. We'll probably want to emit
        # a signal instead...
        #self.hide()
        pass

    def _on_max_button_clicked(self, button):
        if button.get_icon_name_normal() == 'compact-maximize':
            button.set_icon_name_normal('compact-restore')
            button.set_tooltip_text(_('Restore'))
        else:
            button.set_icon_name_normal('compact-maximize')
            button.set_tooltip_text(_('Maximize'))