State of Unicode display support on Windows

["Óscar Fuentes" <ofv@wanadoo.es>]

Some characters display fine on GNU/Linux but not on Windows. An example
is FISHEYE (?\u25c9) with the Consolas font. Apparently, that font does
not include that character. In GNU/Linux Emacs simply uses DejaVu for
displaying the character, but not on Windows, where a white space is
displayed (the Windows machine also has DejaVu installed.)

Is this a known limitation or a bug?

This is the output of M-x describe-char on Windows XP:

        character: ◉ (9673, #o22711, #x25c9)
preferred charset: unicode (Unicode (ISO10646))
       code point: 0x25C9
           syntax: w 	which means: word
         category: .:Base, j:Japanese
      buffer code: #xE2 #x97 #x89
        file code: #xE2 #x97 #x89 (encoded by coding system utf-8-dos)
          display: by this font (glyph code)
    uniscribe:-outline-Consolas-normal-normal-normal-mono-20-*-*-*-c-*-iso10646-1 (#x03)

Character code properties: customize what to show
  name: FISHEYE
  general-category: So (Symbol, Other)