Quickie canvas question

[Eric Sandeen <sandeen io com>]

While we're on the subject of Gnome Canvas questions, here's a quickie
(I think)

I was looking at doing a VU-meter type display, and I have a pixmap that
is the entire VU meter, from green to red [R...Y...G] like that.

I was hoping that I could make the entire pixmap an item on the canvas,
and then only show a portion of that item, depending on how high the
meter should be.  I've done a  

item = gnome_canvas_item_new
and a
gnome_canvas_item_set

but it doesn't look like there's anything I can do to the canvas item
to, for example, show only the left half of it.  I can move, rotate, and
scale to my heart's content, but is there a way to mask off a portion of
the item, or will I need to fall back to GDK functions to do this?

Thanks,

-Eric