On dark themes, the text background is usually a dark colour and the text is a light colour. The text box displaying the debug output of the previewer has the background hard-coded to white, so on a dark theme, the text is barely visible. Reproducible: Always
Created attachment 77823 [details] Use default background colours for the konsolepreviewer
Hello, Can you open a review on git.reviewboard.kde.org, in order to review your patch? Also could you provide us with a snapshot?
I can reproduce the issue.