which child of my box is the one currently "activate"?

[Ignacio Nodal <inodal teleline es>]

Hi, I've a class (written in C++) whith a GtkGLArea and several 
callbacks connected  to button_press_event, button_release_event, etc...
I call it GGLSurf.

Now I want to use this class in another one to insert two GtkGLArea 
widgets in my Application. This new class is not a subclass of GGLSurf, 
it only has GGLSurf* as members of it.
I've created an horizontal box and pack the to widgets in it. I also 
have several dialog windows to change values in the scene (lights, 
camera, fog, etc). The problem comes when I try to use the dialogs 
windows for both GtkGLAreas.

_GGLSurfs is an array pointing to all my objects of the GGLSurf class, 
in this case just two:

GGLSurf*   _GGLSurfs[MAX_GGLSURFS];
guint      _current_gglsurf;
guint      _num_gglsurfs;


And all the elements in these windows are relative to _gglsurf, which is 
declared as:

#define _gglsurf _GGLSurfs[_current_gglsurf]

The problem is I don't know how to update "_current_gglsurf" since the 
callbacks for button_press_event, etc. are all in GGLSurf.hpp. How can I 
updat my "_current_gglsurf" from outside this class? Is there any way to 
ask, for example, which one of the childs inserted in the box is 
"activate"??

Thanks