Does anyone have a link to a good reference on using the Theme API? Here's
what I'm trying to do:

I'm modifying a project I got off of CodeProject. It's a collapsible group
box. This control has a standard plus/minus graphic, but it's always a
simple black-and-white image. That's fine for people like me who run
Classic, but it wouldn't look right for Luna or most anything else. So I
want to be a good citizen and draw the themed expand/collapse images. I have
determined that they are the TVP_GLYPH part with the GLPS_CLOSED and
GLPS_OPENED states, but I don't know how to go about drawing them. Would it
be DrawThemeIcon()? If so, how do I use it? Language isn't important; I can
read both VB.NET and C#.