gtk-- and gl

[Brian Alexander Martin <briam cats ucsc edu>]

I've been trying to convert the glgtk.c file from

ftp://ftp.gimp.org/pub/gtk/contrib/glgtk-demo.971104.tgz

to gtk--.  I've got it compiling and putting up a window, but the openGL
stuff just doesen't seem to want to display anything.  I think the problem
is related to a pretty big hack I made at one point.

The problem is that I need to find the GdkWindow structure associated with
the Gtk_DrawingArea I want to render openGL to.  In the c version this was
done by accessing the window element off of the drawing area.  The window
element is in the _GtkWidget structure.  I was having problems figuring
out how to do this with gtk--, and eventually I came up with the following
beast:

        (((GtkWidget *)(((Gtk_Widget*)glarea)->gtkobject))->window)

The c version was this:

        glarea->window

What I had to do was to cast first to a Gtk_Widget * to get the gtkobject
element (C structure) and then cast to a GtkWidget * (again C) to get to
the window element.  This compiles and runs, but I don't get any openGL.

Any ideas?

thanks,
Brian