Re: gtk_grab_add() and key press events

[Owen Taylor <otaylor redhat com>]

Tim Janik <timj gtk org> writes:

> On 2 Feb 2001, Owen Taylor wrote:
> 
> > While working on one of the older GTK+ bugs:
> 
> >    /* Other events get propagated up the widget tree
> >     *  so that parents can see the button and motion
> >     *  events of the children.
> >     */
> > -  while (!handled_event && widget)
> > +  if (!handled_event)
> >      {
> > -      GtkWidget *tmp;
> > +      while (TRUE)
> > +	{
> > +	  GtkWidget *tmp;
> > +	  
> > +	  handled_event = !GTK_WIDGET_IS_SENSITIVE (widget) || gtk_widget_event (widget, event);
> > +	  tmp = widget->parent;
> > +	  gtk_widget_unref (widget);
> 
> when an event destroyed a widget and its parent and erroneously returns
> FALSE, the below gtk_widget_ref (widget); might go to hell. granted,
> the old code had the same problem, it just occoured to me.

Hmmm, I don't see the problem.

widget->parent always references widget if non-NULL.

So, after:

> > +	  handled_event = !GTK_WIDGET_IS_SENSITIVE (widget) || gtk_widget_event (widget, event);
> > +	  tmp = widget->parent;

either tmp == NULL, or widget has a refcount > 1 and tmp is valid.

Unreferencing a widget with a refcount > 1 can't cause anything to
happen, so after:

> > +	  gtk_widget_unref (widget);

tmp is still either NULL or valid

> > +	  widget = tmp;
> > +	  
> > +	  if (!handled_event && widget)
> > +	    gtk_widget_ref (widget);
> > +	  else
> > +	    break;

And so this works fine.

Regards,
                                        Owen