VLC fails to render subtitles using multiple fonts.
If VLC opens an .ass subtitle file, it renders the subtitle using multiple fonts.
If VLC opens other subtitle formats, it redners subtitles using only one font.
The result is that some chinese characters absent in a font are displayed as squares.
An example is attached as a jpg file.
I used VLC 1.2-git 2011 Aug 27.
I think the solution is to giving VLC an option to force using the ass subtitle renderer for every subtitle format.
mplayer already has such an option "-ass".