graphic bug: audacity 3 mixer board with 'a run' of broken pixel

i’ve begun using audacity 3.1.3 [AppImage] recently and i have noticed a graphic bug: when opening mixer board
a broken pixel appears running from right to left stopping near the slider if i touch mixer’s ruler [slider’s markings].
it is resembling ‘a run’ on nylon tights…
it happens every time i cross slider’s markings with mouse pointer.
i was making custom interface theme when noticed this glitch so firstly i supposed it’s an issue with custom
theming but it occurs with ALL PRE-INSTALLED themes too.
it DOES NOT OCCUR with audacity 2.3.3 from ubuntu repository.
BUT audacity 2 had a tooltip showing current gain level with its top aligned just where that ‘run’ occurs…

i am not sure still should i report this bug to nouveau developers or to open an issue on audacity’s own forum.
maybe video driver or other low-level components are just fine.
i now cross-posting is a bad thing but i want to be sure of my software free from the issues so i am trying to.

here are the screenshots:
a. it is a moment i have noticed this graphic bug while making custom high contrast theme for audacity 3
a bug in graphic memory handling Screenshot_2022-04-27_16-03-34.png
b. it is shown again with nearly completed theme and captured mouse pointer
audacity mixer board with 'a run' Screenshot_2022-04-28_22-17-10.png
c. it is a screenshot showing audacity 2 with a tooltip telling gain level [no bug is seen in old version]
audacity ver2 mixerboard`s tooltip Screenshot_2022-04-28_23-39-45.png

The slider button appears to be missing in your custom theme.


Perhaps you could post a screenshot with the default “Light” theme. I suspect that you are seeing this issue: Linux: Clicking on track slider fails to display value · Issue #1709 · audacity/audacity · GitHub