SUMMARY
Keystrokes can't apply some settings.

STEPS TO REPRODUCE
1. Run systemsettings.
2. Go to settings such as appearance: plasma style, colours (possibly/probably others: check all.)
3. Select new option and try keystroke (either doesn't exist or doesn't complete processing.)

OBSERVED RESULT
Keystrokes can't apply some settings: plasma style no longer has standard underlined-letter buttons indicating <ALT><letter> keystrokes to 'apply' nor 'cancel' (though <ESC>) cancels; ) colours accepts <ALT>a but never processes it (both may leave user hanging and force slow mouse usage.)

EXPECTED RESULT
Allow & process consistent standard underlined-letter button keystrokes ('apply' usually being <ALT>a or sometimes <ALT>p, <ALT>l, or <ALT>y but should be same/standardized/consistent for all cases (no menu uses those letters for other buttons) and include keystrokes for 'cancel' and all systemsettings buttons.)

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: KDE Neon User 5.25.2 (up-to-date,) Slackware64 15.1-current (up-to-date ) / 5.25.2
KDE Plasma Version: 5.25.2
KDE Frameworks Version: 5.95.0
Qt Version: 5.15.5 (Neon,) 5.15.4 (Slackware)