void* mframe_get_prop (MFrame * frame,
    MSymbol key)
@brief Return property value of frame.
The mframe_get_prop() function returns a value of property @b key
of frame @b frame.  The valid keys and the corresponding return
values are as follows.
        key             type of value   meaning of value
        ---             -------------   ----------------
        Mface           MFace *         The default face.
        Mfont           MFont *         The default font.
        Mfont_width     int             Width of the default font.
        Mfont_ascent    int             Ascent of the default font.
        Mfont_descent   int             Descent of the default font.
In the m17n-X library, the followings are also accepted.
        key             type of value   meaning of value
        ---             -------------   ----------------
        Mdisplay        Display *       Display associated with the frame.
        Mscreen         int             Screen number of a screen associated
                                        with the frame.
        Mcolormap       Colormap        Colormap of the frame.
        Mdepth          unsigned        Depth of the frame.
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  Copyright (C) 2001-2011 National Institute of Advanced Industrial Science and
    Technology (AIST)
  
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