#1 Minor judder when resizing wxDockHosts

[Mark]

After the drawing changes to allow wx2.5.1 >
compatibility there still exists a slight judder when
dragging a wxDockHost (live update - on).

This is due to the SetSize() call within wxDockHost
doing a ::MoveWindow( ... TRUE ) which immediatley
redraws the wxDocHosts children - but BEFORE they
have been resized to fit the changed wxDockHost size.