Re-think the TK GUI in the light of the new TK v9.0!

[otizonaizit]

27 years after its last release, a new release of TCL/TK is out:
https://www.tcl-lang.org/software/tcltk/9.0.html
it seems to support a lot of the stuff we always wanted, including better unicode, SVG and scalable graphics.
I don't know when this will be available in Python, but it may save us the trouble of migrating to a different toolkit altogether.

[Debilski]

Remains to be seen if this gives us anti-aliasing and predictable button colours.

[Debilski]

Built-in widgets and themes are scaling-aware

Sounds good. Unfortunately no info on whether the Tk canvas has anti-aliasing on non macOS systems and how well its alpha-channel capabilities work.

[Debilski]

Anti-aliasing is still not here but SVG works with Tk 9.0. It does look indeed a bit more defined than what we have been doing manually with the ghost ‘feet’. (But maybe it would be possible to improve on our solution as well.)

NB: This is not the final ghost design, it is just the SVG I had lying around for the web viewer. We can still decide to have it as close to ‘our’ design as possible.

[Debilski]

Slight problem: Tkinter needs the external library; we may have to support both versions in parallel until all systems have upgraded to 9.0.

[otizonaizit]

Well, in any case we can't proceed until this is fixed python/cpython#124111

And even then, this may mean that we have to drop compatibility with Python <=3.13... Not sure how we can do it. Supporting both the old and the new TK seems like a lot of work in an area of pelita that is already very messy?

[Debilski]

Simply plugging in SVG graphics for the sprites when Tk9 is available, while keeping the old implementation around, is probably doable. But yeah, any change greater than that will become painful. (Plus there needs to be some testing: Should the walls also become SVG? If so, how long does it take to generate and render them.)

We should probably target the stateless rewrite that I’ve sketched in #819 first.