Hi again,
I disabled all extensions except for VisualGDB. As you recommended, I manually changed one color. However, this color also broke when it happened again. After switching between the default blue theme and One Dark Pro, the colors were right, including the manually altered one.
I disabled VisualGDB and used One Dark Pro for some normal Qt programming. No random changes of the colors occur. In my opinion, it must be the combination of VisualGDB and One Dark Pro.
Do you have any suggestions what the cause of this?
Mario