kcms/lookandfeel: show appropriate tooltips for disabled delete buttons
requested to merge ngraham/plasma-workspace:show-appropriate-tooltips-for-global-theme-disabled-deletions into master
Reason for the change
The user will want to know why the delete buttons are sometimes disabled; let's tell them.
Test plan
Open Global Themes KCM and hover over the delete buttons of all of your installed global themes.
Screenshots or screen recordings
Bugs fixed
Part of systemsettings#38.