The Use Custom Font variable controls whether a Text object uses a premade .fnt file (if true) or if it Gum automatically creates font files according to the Text’s Font, Font Size, and Outline Thickness variables.
Use Custom Font is false by default.
If Use Custom Font is set to true, then Gum displays the Custom Font File variable, which can point to a .fnt file created by Bitmap Font Generator.
If Use Custom Font is set to true, then the Font, Font Size, and Outline Thickness variables can no longer be set - as they are part of the font file itself.
The Font Scale variable is still available when using custom fonts.
To set a custom font