For reproducing this, simply place the mouse pointer on the taskbar clock and click right mouse button. After this, the context menu should open.
0.4.12-dev-942-36230bb214e9e24d4be99297332e697f43e4454c - the menu opens successfully.
0.4.12-dev-943-e7ad10241f12bb3760d6cdb73fd7077f87ce1cd3 - it does no longer open.
In debug.log I don't see any suspicious output when right-clicking on the taskbar clock.