See the attached screenshots for an example. I guess, these are dropbox selections but they don't expand.
While I can use arrow keys to switch the items, it's just very hard to find the right one without an overview.
BDJ 4.17.3.2
Operating System: TUXEDO OS
KDE Plasma Version: 6.4.5
KDE Frameworks Version: 6.17.0
Qt Version: 6.8.2
Kernel Version: 6.14.0-112033-tuxedo (64-bit)
Graphics Platform: Wayland
Processors: 8 × AMD Ryzen 5 3500U with Radeon Vega Mobile Gfx
Memory: 8 GiB of RAM (5,7 GiB usable)
Graphics Processor: AMD Radeon Vega 8 Graphics
I used the spinboxes because the GTK3+ drop-downs have a horrible UI design (I think Qt has the same issue). I tried to minimize the use of drop-downs where really needed. I wanted to use the spinboxes where the number of selection is about 5 or fewer.
I agree that the 'Locale' selection should be a drop-down rather than a spinbox. There are quite a few selections there. I can change this.
It is interesting that the spinboxes on your computer have X + rather than - + displayed. I don't know what's going on there. That is something internal to GTK3+. You can try using a different theme. And of course, the arrow keys work.
Just for informational purposes: https://bugs.kde.org/show_bug.cgi?id=494086
The X instead of - bug is a KDE breeze theme bug, fixed 8 months ago. There may be other GTK3 icon themes with this bug.
In the configuration, I changed locale, UI theme and marquee theme to be drop-downs. I had to work around a GTK bug in the process. I should be able to run the tests and make a release tomorrow.
Most other text spinboxes have fairly short lists, excepting "display settings". There are a few other text spinboxes that could potentially have more items that is reasonable, but I'm going to leave those alone.
The Locale, UI Theme and Marquee Theme have been changed to use drop-downs in version 4.17.3.3. The other text spinboxes generally have quite a short list of options and can be traversed with the - and + buttons.