Hi Kasper. (Remember me? :-)
I just installed Cadabra2 on openSUSE LEAP 15.1 but immediately encountered the following bug (or is it a feature?).
When attempting to highlight some text (intending to copy or delete it, or whatever), the text seemed to just disappear instead of being highlighted. After a while I realized it's because the highlighted text is actually white on a pale grey background, making it almost invisible.
I tried playing with the "highlight syntax" options, but failed to find anything applicable.
Is there some other preferences setting elsewhere that would fix this? If not, then... how?