Thanks for looking into this. I have tested this again and it does look like it is working as intended in the latest version of mIRC.
I can only assume that someone emailed me some time ago to report the previous behaviour as a bug because they were trying to set a specific window font while at the same time setting it as the default font. Since "Set as default" and "Use default" are meant to be separate settings, that does make sense. However, from a usability point of view, I can see what you are saying.
I could change it so that the "Use default" option is automatically checked if the "Set as default" option is manually checked. Would that resolve the issue?
