fullscreen requests are handled gracelessly

[Ochiruko]

Is your feature request related to a problem? Please describe.
Although there might be a solution out there, it would be really nice if fullscreen requests were handled gracefully by default and "just worked". Currently, with lightly modified kwin settings, making anything fullscreen (e.g. mpv, youtube, firefox) WILL cause it to be ignored by polonium when it exits fullscreen.

Describe the solution you'd like
I'm not entirely certain of why the issue happens, but I imagine that the situation is simply not supported yet. I'm aware that polonium is still very alpha, but if this isn't on the immediate roadmap, which it probably is, I think it would not be a bad idea to start considering putting it on there, as I think it is a feature that many of us use quite a bit. An easy solution (and I am not familiar with the internals of polonium, so this might not work of course) would be to simply have polonium reevaluate those windows whenever anything of note happens, including fullscreen calls to kwin (also not sure how that works, I'm strictly a user in this particular domain). The main issue with that, I can imagine, would be that we would have to figure out a way to maintain the layout (if you do something, then undo something, you should be back to the way you were before, right?) but I think that the fullscreen issue is the bigger issue here, and invertibility is a QoL thing for a more mature polonium to deal with, in my opinion. Of course, all of this is strictly theoretical, as I have no idea how polonium actually works.

Describe alternatives you've considered
A description of what kwin settings are necessary to make polonium work nicely with fullscreen on the polonium readme.

[zeroxoneafour]

It would be nice, wouldn't it?

It used to just work. There's a large amount of code in the project dedicated solely to placing fullscreened windows back into approximate tiles (code shared with minimizing, maximizing etc.) I personally tested it with decent success with Konsole a while back.

Unfortunately, while Plasma 6.0 and 6.1 are both supported and with 6.1 being much buggier, a lot of stuff has broken. I'll update it probably after everything is more stable (unless that never happens, I wouldn't be surprised)