Signal handling questions

[Dov Grobgeld <dov grobgeld gmail com>]

While playing around with a general system for doing polygon overlays (e.g. for rectangle or line selection) I got stuck on the following problem.

Assume that I have a widget A that has an expose handler exp_A().

Now assume that I would temporarily like to draw an "overlay on A" from the code in expose handler exp_B(). I.e. after exp_A() has finished its work, exp_B() should be called.

I am in control of exp_B() but cannot touch exp_A().

I trigger the calling of expose events by calling gdk_window_invalidate_rect() from update_B().

The problem is as follows:

• If I do g_signal_connect_after(widget, "expose-event", exp_B, me) then I set up the correct order of exposure through A and B, but if exp_A() does "return TRUE", then exp_B() will not be called.
• If I do g_signal_connect(widget, "expose-event", exp_B, me) then exp_B() will always be called, but in the wrong order.
  

So how is can this be solved?

If I do g_signal_connect(), can exp_B() e.g. block itself as a signal handler and rethrow() the signal to the other handlers and then return? How is this done?

Thanks!
Dov