Pseudo transparent backgrounds not working with large resolutions

[DeluxeEgg]

Upfront Information

$ fvwm3 --version fvwm3 1.0.4 (released) with support for: ReadLine, XPM, PNG, SVG, Shape, XShm, SM, Bidi text, XRandR, XRender, XCursor, XFT, NLS

Gentoo ~amd64

$ uname -sp Linux AMD Ryzen 9 7950X 16-Core Processor

Expected Behaviour

I recently purchased two displays that create a combined resolution of 5120x1440. I have been using pseudo-transparencies for years with my older 3840x1200 setup and everything worked correctly (i.e. transparent background in the pager).

Actual Behaviour

After starting FVWM with the two new displays, pseudo-transparent backgrounds no longer work and appear as a grey background instead. Reducing the resolution of the displays permits the pseudo-transparent background to work properly again (even without a restart of FVWM).

Enabling logging

Nothing appeared in the log file

Steps to Reproduce

Set a resolution of 5210x1440 or higher and pseudo-transparencies stop working.

Reduce the resolution and they work again.

Does Fvwm3 crash?

No, FVWM continues to run.

Extra Information

For some background, I use pseudo-transparent backgrounds with a number of other applications outside of FVWM (terminals, system monitors, etc.) and they still work properly.

I am running FVWM-Crystal as the theme and confirmed it is not and issue with that.

[ThomasAdam]

Pseudo-transparency, via ParentialRelativity?

[DeluxeEgg]

I would assume it's using ParentialRelativity (provided my understanding of that is correct). Specifically, the pseudo-transparency that no longer works in FVWM is when it's using the root background to create the "transparency" (for example, my menu background) - different than when using "true" transparency as with a composite manager.

[dumblob]

Any insights why this is "not planned"?