CLONE -Nested QDockWidgets show erratic behavior when resizing manually

Starting with Qt 4.6, resizing dock widgets in a main window that has nesting enabled fails. The handle between two adjacent dock widgets, when dragged, moves much faster (looks like something exponential) than the mouse pointer that's supposed to drag it.

Way to reproduce:

1) Start the Qt Demo "Main Window"
2) Allow nested docks (menu entry)
3) Drag the White Dock next to the Black Dock so you have two adjacent dock widgets
4) Enlarge the area (drag right-hand border of the White Dock to the right) so you have leeway to resize in the next step
5) Move the resize handle in between the Black and the White Dock
6) Notice how the resize handle moves much faster than your mouse pointer
7) Profit

This can be done similarly for vertically stacked docks as well.