[RMVX ACE] VERTICAL LINE SPACING IN DIALOGUE BOX

Off the top of my head, I think it might have to do with the line_height function, which is in the Window_Base class. They hard-coded a value in there (24, to be precise) that has no basis on the font you are actually using.

One option is to fiddle with that number until you get the desired spacing. Another possibility is to use contents.font.size, and see if that gets you the desired spacing.