At least don't infinite loop if the widget and window heirarchies don't

At least don't infinite loop if the widget and window heirarchies don't

Fri Jan  4 13:05:15 2002  Owen Taylor  <otaylor@redhat.com>

        * gtk/gtkdnd.c (gtk_drag_find_widget): At least
        don't infinite loop if the widget and window heirarchies
        don't correspond.

        * gtk/gtkdnd.c (gtk_drag_find_widget): Handle changes
        in heirarchy in ::drag_motion, ::drag_drop callbacks
        by referencing child widget lists. (Patch from Tim)

        * gtk/gtkdnd.c (gtk_drag_find_widget): Fix a problem
        with widgets where window.x != widget->allocation.