Blacked or whitend text or parts of windows

[tobiasBo]

Hello Mint users,

I guess(!) that since a recent installation and subsequent removal of the xubuntu package gpxsee (app) my cinnamon desktop has theming issues. (Downloaded the .deb file from the Download page of gpxsee)
In detail, some parts of some (!) application menus or window frames turn black or some (!) text in some menus has gone white (on white background). This does NOT happen in the start menu. The applications are ALWAYS the same applications and they are at least:

Rhythmbox (Menu completely black - context menu has whitened text - looks like missing entries)
Nemo (empty folder frame black when not in focus)
Update Manager (black window frame when no updates present)
(Maybe others)

I tried to change the theme from mint-x to mint-y in the theming settings. That fixes the issue! All apps are displayed normally again. So this issue occurs only in theme mint-x.

I would like to reset the mint-x theme or so, but I don't know if that is a good idea.
Other idea would be to purge and reinstall the mint-x themes.
Before I try I would like to hear your ideas.
I use mint 18.3.

Has anyone some suggestions to fix this issue?
I've attached some screenshots.