Quick Launch bar, icons should be repositionable by mouse-dragging

Observed result
Currently the icons in the QuickLaunchBar cannot be repositioned in ros by dragging with the mouse. Their order cannot be changed.
0.4.15-dev-5137-g826bd41_notRepositionable.webm
0.4.15-dev-5137-g826bd41_notRepositionable.log (nothing gets logged then)

Expected result
In 2k3sp2 that is possible in both modes, when the taskbar is fixed, and also when the taskbar is not fixed