Monokai theme print out are unreadable
Printing a text file (filetype: None) with Monokai theme gives an unreadable result. It appears that the text is printed in the text color on the screen: lighter_grey=#dfdfdf. On white paper this is not really visible. This might not be limited to the Monokai theme.
I believe this is a bug in Geany where it doesn't print the background (maybe to save ink?) but it fails to invert/adjust the colours of everything else, leaving it illegible. You might want to open an Issue on the Geany repo, though there might already be an Issue for this particular bug. Another option is to invert the colour theme in Edit->Preferences->Editor->Display->Invert syntax highlighting colours or switching to a dark on light theme while printing.