Symbian Font related
In Symbian there has a linked font technology which means if one font losts some symbols for displaying, another font can be used for that symbols's display. The API is CFbsTypefaceStore::RegisterLinkedTypeface(). After this function calls, a new typeface is created to link these fonts.
In Symbian there has an API CFbsTypefaceStore::SetSystemDefaultTypefaceNameL(), that it can set the system wide default typeface name when requesting a font. E.g. When requesting a CFont using an empty TFontSpec, it will return the fonts of that font spec.

Qt Font
Current Qt does not support Symbian's linked font.

Problem
If a linked font is created and set as system default font, all Qt applications will either crash at the app startup, or display mess. (This could be done by a project name selectable system font in Nokia for China language, that can change the system font to a 3rd vendor's font more offical and normal than FontRouter does.)