Corrupt Emulationstation Buttons

[xenium]

Somehow my dialog buttons (i.e. not the navigation buttons at the bottom, but the "ok", "cancel" type buttons shown on dialog boxes) have become corrupt:

Instead of being rounded rectangles, the highlighted button looks rectangular and the unhighlighted buttons look like rounded rectangles with flat sides.

I was editing a theme when I first noticed this, so I suspect that's what caused it, but I have since deleted my /etc/emulationstation/themes directory entirely and re-installed emulationstation with only the default carbon theme, and it still persists.

Thanks for any ideas.

p.s. disregard the fuzziness of my screen shot, that's due to my running at 240p and not related to the problem: the buttons looked fine yesterday at 240p. :-D

Pi Model or other hardware: X86 PC, AMD Radeon 7 APU
RetroPie Version Used (eg 3.6, 3.8.1, 4.1 - do not write latest): 4.8.2
Built From: Installed from source on Ubuntu 22.04 (https://github.com/RetroPie/RetroArch.git)
USB Devices connected: N/A (it happens without anything connected)
Controller used: N/A (it happens without anything connected)
Error messages received: None
Verbose log (if relevant): N/A
Guide used: (Mention if you followed a guide): https://github.com/MizterB/RetroPie-Setup-Ubuntu
File: (File with issue - with FULL path) N/A
Emulator: (Name of emulator - if applicable) N/A (it's an EmulationStation issue)
Attachment of config files: I'm not sure which ones to include.
How to replicate the problem: I don't know how to.

[xenium]

Well... I just figured out what was causing this, although I still don't understand why it was causing it, so if anyone has any suggestions I'd still like to hear them.

I start EmulationStation with the "screensize" command line parameter, because I'm running at 240p on a CRT with a super-resolution (1920x240), and if I don't do that Emulationstation gets confused and scales things wrong. I then use XWindow's built-in scaling to scale EmulationStation to the full width of the screen.

This morning I changed it from this:

--screensize 300 225

to this:

--screensize 300 222

because a few lines were getting cut off on the bottom. I neglected to change the horizontal though, I should have changed it to 296, to keep the aspect ratio at 4:3. Apparently it was the aspect ratio change, even though it was tiny, that screwed the buttons up.

I had moved on to editing my theme and completely forgotten about making that change by the time I noticed the messed up buttons. Oops. :-)