Prefer the pure python implementation of AUI if available
* reordered window creation to work around wx.lib.agw.aui requiring a top level window before being used
Added initial (very minimal) wx tasks support
* added examples in examples/tasks/steps, each stepX.py to build upon the last
Fixed menubar and toolbar creation
* trait change handlers were missing
Finally figured out where to add central pane -- the AUI manager of the application window
Added Editor support and step2.py demo
* added EditorAreaPane support for adding and deleting notebook tabs
Got rid of a few layers of unnecessary widgets
* ApplicationWindow._create_body and TaskWindowBackend.create_contents aren't needed for wx because the AUIManager handles the layout
Added convenience import pyface.wx.aui to load the AUI toolkit
* prefer the pure python version wx.lib.agw.aui (no seg faults!)
* can select toolkit version by setting environ var ETS_WX_AUI to "wx"
Initial support for a single dock pane
* not sized correctly and not hidden by default, but it's displayed at least
Dock area setting now works and using AUI perspectives for save state
* only commit DockPane trait changes if active task
Added multiple tasks support
* AUI manager now correctly saving and restoring state
Added new interface methods to i_task_window_backend for batch window updates
* added [begin|end]_batch_window_updates as a hint to the toolkit that lots of updates are coming
* the wx ui flashes quite a bit when re-laying out controls, so provides the wx.Freeze/Thaw pairs
Dock area is now honored in initial creation of dock
Initial Tabbed dock pane layout support
Dock panes must be set visible in main_window_layout
* stubbed out EVT_SHOW, but maybe unneeded in wx?
First cut at splitter support
Added nested splitters
* subject to the AUI limitation of only two nested splitters
Fixed hide_task to handle empty notebooks left in the AUI manager
Added wx support for examples/tasks/advanced example
* changed to EditorAreaPane as SplitEditorAreaPane isn't supported in wx yet
* added runtime selection of toolkit in python_editor.py
Check for already destroyed control
* TraitsDockPane destroys the entire pane before calling the superclass
Turn off tool bar item names in examples/tasks/advanced