Change popup_menu signal to return gboolean instead of void. This allows

Change popup_menu signal to return gboolean instead of void. This allows

* gtk/gtkwidget.[ch]:
Change popup_menu signal to return gboolean instead of void. This
allows the keypress which invokes the signal to be propagated to the
focus widgets ancestors if not handled by the focus widget.

* gtk/gtkcolorsel.c gtk/gtkentry.c gtk/gtktextview.c:
Change signature of popup_menu signal handler to return gboolean
instead of void and return TRUE in the signal handler