Supress incorrect resize notifications
There are paths that can lead to multiple resize events that end up back at the same size.
An easy one to reproduce is a split view with the session toolbar enabled but not the main toolbar. The session toolbar belongs to each tab; when we switch view that is recreated by kxmlgui which results in the toolbar deleting and creating causing two resize events on the display.
This patch defers the resize notification until there is a paint at a new size.