When I window select (i.e LMB click-and-drag - no matter which direction) in the viewport (both parallel and perspective) geometry turns black. Since not everybody is seeing this I have now checked on another PC and this is repeatable there.
Then I found out that this is display mode dependent… So here is my display mode: wrmd.ini (11.6 KB)
LMB dragging in the viewport:
LMB dragging and hitting the geometry:
In more complex scenes the blackness is not universal (limitations in dark matter…):