<gtk-widget> -- allocation width

[greg]

Hello,

I am looking for a way to access the allocation width (or height) of a 
widget from scheme;
i.e. I want to say:

        /* get actual widget size */
        width = (GtkWidget*)my_widget->allocation.width;

but in scheme, i.e.

       (define my-widget (make <gtk-drawing-area>))

       ;; do some widget placement

       (get-width-of  my-widget)

I am able to do this by writing a C function that gets the width and 
wraps it up as a
scheme object, but I am wondering if there is a way to do this that 
doesn't involve
any C code.

Thanks,

Greg