Fixing Issue #235 TreeView problem with overwriting selected values at Loaded event with default Items[0] value and not selecting TreeItem because Item was selected before TreeItem was because WPF is LazyLoading TreeItems for Items after Loaded event...
Added comments to code
Fixing Issue #263. Wpf.FrameBackend did not UpdateChildPlacement after setting new Content(child)
Removed part for delayed selecting of VisualItem because it should be solved more generally for all cases. So this pull now only contains fix for issue #235
Merge branch 'master' of https://github.com/mono/xwt
[GTK] add initial Gtk3 support
[GTK] add Gtk3 support for ISearchTextEntryBackend
[GTK] honor size requests with Gtk3
[GTK] fix CanvasBackend sizing issues with Gtk3
[GTK] fix Gtk3 dll names for Windows
Merge branch 'gtk-fixes' into gtk3
[GTK] rename changed Gtk3 TreeModel interfaces to reduce XWT_GTK3 usage
[GTK] add toolkit (gtk2/3) specific extensions to reduce XWT_GTK3 usage
[GTK] move Gtk3 ISearchTextEntryBackend impl to a separate file
[GTK] add a custom Gtk.CellRenderer base with toolkit (gtk2/3) specific implementations
[GTK] revert dangerous try/catch block
[GTK] add a custom GtkViewPort base for CustomViewPort with toolkit (gtk2/3) specific implementations
CustomViewPort must be sealed because of the new adjustment properties for Gtk3
[GTK] add a custom GtkDrawingArea base for ImageBox with toolkit (gtk2/3) specific implementations
Merge remote-tracking branch 'origin/add-text-cursor-selection' into gtk3
[GTK] move toolkit (gtk2/3) specific backend code to separate files