Black "border" when opening browser with Hardware Acceleration enabled

[ZFR77]

I noticed that I didn't have Hardware Acceleration enabled in settings, so enabled it today. However with it enabled, every time I open Pale Moon, a black sort of border appears (see attachment). This usually lasts for 1 sec, but can be 0.5 to 3 seconds. After that everything appears as normal.

If there is a window open already and I open a new one, it happens very quickly. Barely flashes.

Still happens with all addons disabled.

Stops happening when I disable HWA.

I'm using Linux Mint 19.3. This doesn't happen on the Windows version of Pale Moon dual booted on same machine.

It's not a huge deal, but I'm wondering if anything can be done about it?

Thanks.

[Moonchild]

There is a reason that what this option controls (layers acceleration and compositing) is disabled by default on Linux. Enabling it will only work flawless on an as of yet unknown subset of installations.

IOW: enabling this can cause glitches. It's unlikely we can do much about it so if you want those glitches to be addressed you yourself will have to do research and contribute.

[ZFR77]

Sorry, to bump this. But I figured out what was causing this in my case. I had mprime running in the background. Without it, the issue is no longer there.