Created attachment 102150 [details]
Screenshot showing the artifact

The full desktop zoom (Zoom Factor: 2.0, Mouse Pointer: scale, Mouse Tracking: proportional) shows semi-transparent artifacts seemingly caused by not scaling and panning graphical the translucency part of elements like the task panel, tool tips, or popups (non-classical windows, like the calender or the volume info that pops up when I hit the volume keys),.
Thus, e.g. with a task panel at the bottom, upon zooming, one gets a semi-transparent stripe spanning the bottom of the screen having the height of the panel. The height of that translucent stripe stays the same with increasing magnification, i.e. does not scale proportionally.
When I hover over some items in the systray, I get translucent rectangles the size the pop-up would have been had I not zoomed. These don't move, i.e. stay at the position of the unzoomed element even when panning.