Creates a pixmap and a mask bitmap which are returned and renders a
pixbuf and its corresponding thresholded alpha mask to them. This is
merely a convenience function; applications that need to render
pixbufs with dither offsets or to given drawables should use
drawPixbuf, and
pixbufRenderThresholdAlpha.
The pixmap that is created uses the
Colormap specified by
colormap. This colormap must match the colormap of the window where
the pixmap will eventually be used or an error will result.
If the pixbuf does not have an alpha channel, then the returned mask
will be
Nothing.
Removed in Gtk3.