Things that I've done:
- I've tried the settings on different monospace fonts (all under 16pts)
Also I have some difficulty finding Hiraki-marugothic16-iso10646-1.fnt (default detailtext font).
I've understood that I have to have the Qt environment in order to run the theme editor, I'll have to get back on this when I have the chance to set it up on my Ubuntu-based machine in my virtualbox.