Bug or feature? Zero encoding priority when Avidemux is not on active VT

[flittermice]

I like using the Linux feature "virtual terminals" on a regular basis, i.e. I switch users with Ctrl-Alt-F2, Ctrl-Alt-F3...
However, when I start any encoding job on one VT and switch to another VT, Avidemux would simply pause encoding until I switch back to the VT where Avidemux is running and would then continue. I tried to change the nice level of Avidemux but this didn't change anything.
Is this a bug or a feature and how can I get rid of this behavior?

I'm running Arch Linux, Gnome Shell and Avidemux 2.8.0. However, I encounter this behavior since years.

[eumagga0x2a]

how can I get rid of this behavior?

By using the command-line executable of Avidemux? I suspect the graphical (Qt) executable needs the ability to refresh the display (to update the encoding dialog).

Totally unrelated to the nice level.

[flittermice]

Well, I use ffmpeg where I can.
Your diagnosis is comprehensible to me. But there are so many programs around that don't stop working when they are not "seen". Maybe it's a Qt peculiarity but I can't tell because I don't use many Qt programs elsewhere.