Just did upgrade Xubuntu 16.04 LTS to 18.04.2 LTS with help from a friend via terminal; my reason was to be able to use my updated LinHabu 19 (accounting software) which needs at least 16.01 and was changed to GTK+ 3. Now everything is up and running, the programme is functional, but the menu buttons and the graphic lineout are not displayed correctly. In the documentary of LinHabu is said this can happen, but it does not specify the exact package. it just says oxygen-gtk would not work correctly and where you find settings in KDE and i do not know where to start really...
Same case in the Lighning calendar i use with Thunderbird. Everything works, but editing menues are missing lines and it looks all weird.
How could i find out which theme i am working with and which one i should? And how do i have to implement it? If somebody could help just telling me command lines, i probably will get along; so far i never did any compiling or configuring themes because i do not care about the visual so much, as long as thing are functioning,but this is a bit much. Thank you very much for suggestions!
