On an x86 system using Cinnabar Build 40rc4a
Open gnopernicus.
Start Mag
Set zoom level on X and Y greater than 3.
Other settings should not hinder reproducing the bug.
Once Mag is set up Press Ctrl+Esc to open Launch Menu.
Notice the behaviour, it is not 100% reproducable but
I have observed:
Magnified screen turns fully/partly black
Some or all of Launch menu is invisible.
Another issue is that most windows on the desktop are still visible after they have been shut down and will only disappear when the pointer has been moved around the desktop a number of times.