Drag and drop not working in QTDesigner or QTCreator designer

This has upset me for some time and I finally found a forum entry solving this problem.

The problem: I wasn't able to drag&drop in QTDesigner any widgets from the widgets list to the form I was editing.
Solution found here: qtforum.org

You only need to add this entry to your /etc/X11/xorg.conf:

Section "Module"
Load "extmod"