From the Help online scratchpad:
Tab colors - Currently to difficult to see as it's so light, both background and foreground, so simply have the hover-over color as the default and maybe put a darker 1px border color around them
File to touch
Ilmari Lauhakangas committed a patch related to this issue.
It has been pushed to "master":
tdf#114709, tdf#112758, tdf#112757