0.4.12-RC-46-g317ca41 gcc dbg lin is affected.
Somewhen around 0.4.12dev'ing we implemented analogon to 'MS Aerosnap', that allows you to snap a Window to the screen borders via Winkey+Cursor key.
-uncheck the checkmark that 'fixes the taskbar' to be able to freely move it
-drag it to the right screen border, you will most likely see the first malfunction here, as it often 'wants' to expand to 50% screen size
-when now moving it by pressing Winkey+arrow-up, Winkey+arrow-left, winkey+arrow-right, winkey+arrow-down you will soon enter a state where it's getting totally impossible to interact with the taskbar anymore. Only way out is killing the explorer
Make sure, Aerosnap is ineffective for the taskbar 'Window'