The toolbox is something I initially based on some hacks in Qt3, but those didn't really seem to work the same in Qt4 leading to rather a broken toolbox.

The correct solution was to write my own layout manager so I did.
The layout now is heightForWidth() capable, but QDockWidget does not yet support that. I hope to change that in the future to have even better usability for the toolbox.

A huge advantage of this toolbox is that the 2-columns concept is no longer hardcoded.
The layout is much more dynamic.