matching curor on other windows - how?

I have multiple windows that each contain a GtkGLArea for viewing
remotely-sensed images. I would like to display a cursor (that follows
the main cursor) in the other windows. I was redrawing the other
windows, based on the motion-notify in the main window, and then just
using openGL to draw a simple crosshair cursor. Well this works, but the
cursor is irritatingly jerky. Yeah, hardware acceleration helps a lot,
but I don't want to depend on this. I really don't need/want to redraw
the underlying image! I found that I could just make_current, use opengl
to do a GL_COLOR_LOGICAL_OP with an XOR, write where my cursor was and
then the cursor's new position, swap_buffers. Yeah, this is much faster,
but I really would like to have a cursor where I could specify the
color! I have combed the web for information on other options and tried
to understand overlays, but I must confess I'm a newbie and this seems
tied to hardware more than I'd like and not that straightforward. I
guess I'd really like to understand how the gtk cursor renders to the
active display without having to redraw the underlaying image each time.
Understanding that I might have a clue how to proceed. I see no way to
directly use gtk_cursor to help me out here. Can someone help enlighten
me!?!?! 

Thanks,

Diana Esch-Mosher