Menu Bar Transparency & Flicker Issue

[tamj]

ST4 v.4121
Ubuntu 20.04.2
Dell Inspiron i5 7XXX >> External monitor via HDMI-VGA adapter.

Lately I have observed desktop icons somehow coming through the menu bar space on Sublime Text 4.
There is also a darkening of the usual grey background when Quick Switch Project… is selected. After clicking and use of the arrow keys the background turns grey again.
But this should not be happening in the first place.
I sometimes observed flickering as I hover up and down across the project files on the left sidebar.
What on earth is causing this ?

[bschaaf]

Are you using hardware acceleration? Note the menu bar is drawn by GTK not us and GTK3 has known issues with hardware acceleration.

[tamj]

I believe that hardware acceleration is active, yes.
At any rate I have configured my browsers to use it and I see what appears to be a launch option for all graphics or computational intensive applications - see image below.

I also threw out MD viewer plugins that I’d installed round the time this issue started:
MarkdownPreview and MarkdownLivePreview.

[bschaaf]

You can disable/enabled hardware acceleration in the settings.

[tamj]

It definitely IS enabled:

$ glxinfo | grep "direct rendering"
direct rendering: Yes

Precisely where in the Settings ?
It’s not a visible option in either Appearance, Screen Display or Tweaks.

[bschaaf]

Please check the Sublime Text settings. If you’re using hardware acceleration with ST then you’ve got it specifically enabled in your settings.

[tamj]

Please check the Sublime Text settings. If you’re using hardware acceleration with ST then you’ve got it specifically enabled in your settings.

Looks like I amended this over the last 6 months on advice from some YouTube video or other.
Removed

"hardware_acceleration": "opengl"

from ST settings.

Dropdown menus now clear as before, no flickering, no transparency in top bar of ST window.