I posted this a while back but cannot find the original thread, it's not really a major problem just an annoyance I've come across.
Anyway, when changing the font of a minimized window via right-clicking on the switchbar button and selecting font, mIRC does not save the changes made.
Type //echo -a $window($active).font - $window($active).fontsize in the status window.
Minimize the status window and right-click on the button, selecting font.
Change the font to anything else.
Restore the status window and you can see the font hasn't changed, type //echo -a $window($active).font - $window($active).fontsize again just to be sure.
Using the /font command on a minimized window, in this case /font -s ..., changes the font without a problem.
Windows XP Pro, mIRC 6.17