Window shadows are borked for me in AC mode. This bug *seems* to affect amdgpu and noveau users, but not Intel graphics.
After some debugging with Company we determined "the shadows are NOT messed up in the image passed to gdk_window_end_paint_internal()" and that "we use OpenGL (in gdk-wayland) to send the window contents to the compositor and it seems that is going wrong once Webkit gets involved"
OK, I just noticed this is affecting Yelp too. This is bad. I think we need to disable AC mode by default at the WebKit level until it's fixed. Apps that want it can opt in.
This issue does not affect Fedora 30, but it does affect the GNOME master runtime.
I was hoping this was fixed in bug #193903, but sadly not.
FTR, today checking things a bit with Michael he noticed that this
happens both with WEBKIT_HARDWARE_ACCELERATION_POLICY_ON_DEMAND
So at least we know it's nothing related to the on-demand activation
of AC... which is not much new to know, but may help a little bit.
This appears to have fixed itself sometime in the past three months.