[gtkmm] Creating new Pixmap?

["David B. Davis" <dbdavis dbd-associates com>]

I've been spinning my wheels a couple days now trying to create a 
Gdk::Pixmap.  Most of the .create* methods take a RefPtr to a Drawable, 
and I cannot figure out what Drawable to pass!

Perhaps I am not using the optimum tactics: I want to read an image 
file, add some simple line drawing (so I need a Drawable, I assume a 
Pixmap), then scale it up (presumably in a Pixbuf, not a Pixmap) before 
setting it into an Image.  I've had no problem reading an image file 
(.pgm) into a Pixbuf, scaling it and displaying in an Image, but moving 
from Pixbuf to Pixmap and back just isn't working for me.

Can someone give me a hand here?

Thanks,
David