I believe that a ListBox can only have one font for all contents. By putting in a Delay 50, I can see as each font is loaded - all the text in the ListBox changes to that font.
As for defaulting to Arial - when some fonts are loaded, they don't seem to load properly. At those points, I see all text return to Arial.
As for defaulting to Arial - when some fonts are loaded, they don't seem to load properly. At those points, I see all text return to Arial.