Emacs-cvs doesn't display multi-column unicode

[lpjhjdh]

Hello.  I built emacs-cvs with gtk and xft, but none of the characters
in supplementary-arrows-a (e.g. 27f9 ⟹) display (just get a block).  I
know the fonts I tested (bitstream vera sans mono & deja vu sans mono)
have the characters in question and terminal emacs displays them
fine.  Most other unicode characters display.  One exception I've
noticed are the brackets 27e6 ⟦ and 27e7 ⟧.

Any ideas?
Thanks.