I had this trouble in Ardour3 before and it seems to be related to KDE. Anyway: an application for Linux should be usable in any major Linux DE OK? I tried to fiddle with the GTK-Settings in KDE but to no avail.
Now I see, that the problem occures in Plugin-GUIs also. And when I open CALF with its own GUI I do not see the problem. The GUI is perfectly the same as in XFCE or GNOME. But running the very same Plugin in Ardour shows white strings on white background…
So all I would like to do is find a fix for myself(that could maybe help others who run KDE also)
Where can I search?
Is it possible, to hack the XML-Themefile? Is it possible to do something at build?
Any help and hint would be most appreciated.