I am using Pidion phone with WM6.1.
When i set the regional language to thai (or other such as Vietnamese), only icon label or text header are able to seen. Button or text box all will turn to square box. (Example clock and time show in little square box)
I google it, but most of the solution told to add font or install font cab file but it seem useless.
The fonts used are missong the thai glyphs. Just install a full unicode font (~20MB) or fonts that contain unicode thai glyphs.
Se here for how to get and test a font and it' unicode glyphs: http://www.hjgode.de/wp/2011/04/06/mobile-development-a-simple-unicode-character-map/