The desktop bg: just as compatible as any wallpaper app can get it (full mouse & keyboard input; no known issues, no keyboard input for the desktop icons, no uwp app support.)

The lockscreen bg: near identical to the desktop bg in compatibility, but some apps don't run on it, and chrome does not have sound. but other than that, the lockscreen bg supports most apps, with full input and some will play sound, no uwp apps.

The taskbar bg: less compatible than desktop bg since all supported apps as far as input are the same, but some won't scale to the tb, move to the tb, or etc.

all other bgs: they are all different but as a whole, only very few apps work, seems to only be specfic win32 apps.

accent colors for file explorer's file browser and notepad: it fully works. the text and dragbox colors change to a color of your choosing.

tested apps: geometry dash - works on lockscreen and desktop, fails on others since it does not scale.

mari0: AE: works on taskbar bg, desktop bg, and rightclick menus, not lockscreen. does not work reliablt on all other bgs.

rainbow swirl theme: works on all bgs.

mario 64: works on all bgs, stretches perfect to them too.

mp4 files: works on all bgs.

chrome: lockscreen, sometimes taskbar bg (unreliable), desktop bg, and nothing else.

images (via my images.exe image previewer; I made it into a .ppwt theme that bundles the image and the player) all bgs.

dolpin emulator (running super paper mario): all bgs. but lockscreen cuts sound on lid close then reopen.

give up robot 1 & 2 (a flash game series): it works on desktop bg, lockscreen bg, technically on tb bg but scale is undesirable since it has black bars that crop it to the start button and the rest is black. taskbar utils works, didn't test it on the others.

feel free to give feedback on my main page to add more to this list.