Dock resize does not work correct if AllowNestedDocks is enabled

When enabling AllowNestedDocks dock resizing by mouse does not work correct. The divider moves faster than the mouse.

How to reproduce:
*Create a new Qt GUI project with QMainWindow
*Set the mainwindow dockOptions to Animated Docks | AllowNestedDocks
*Insert four docks in the main window (two at the bottom (or top), two at left (or right))
*Compile and start the app
*Drag the docks from the bottom such that they stacked above each other
*Drag the docks from left such that they are side by side
*Now drag each of the drag handles to change the space amount between the docks and see what happens.