Re: View hierarchy problem

[Andreas Höschler]

Hi Fred,

> Andreas Höschler wrote:
> > Hello all,
> >
> > I have an application with a shelf view that has a bunch of subviews
> > (icons representing applications). In windowDidBecomeKey: I reload the
> > shelf, meaning that I do removeFromSuperviewWithoutNeedingDisplay for
> > all these subviews and then rebuild the shelf (recreate all the
> > subviews). Doubleclicking on one of these subviews launches or 
> > activates
> > the represented application.
> >
> > From time to time I get a core dump when doubleclicking from one app 
> > to
> > the next on the shelf. By backtracing I found out that
> >
> >     [NSWindow makeFirstResponder:];
> >
> > is called with a previoulsy removed (and released) view (one of the
> > views that have been recreated earlier in windowDidBecomeKey:). Here 
> > is
> > a pseudo backtrace of this
> >
> >     [NSWindow makeFistResponder:]  <--------
> >     [NSWindow sendEvent:];
> >     [NSApplication sendEvent:]
> >     [NSApplication run]
> >
> > I realized some code in [NSView removeSubview:] that is obviously 
> > meant
> > to remove the to be removed view from teh view hierachy, but it seems 
> > it
> > is still retained by some event circling around in the event loop and
> > then causes the malfunction.
> >
> > Any idea how this error can be prevented or further tracked down?
>
> No, really no idea how this could happen. The view used in sendEvent 
> for
> makeFristResponder comes from a hit test on the window view (_wv). This
> means your removed and released view must still be in the window 
> hierarchy.
> Ah, now I see the issue: this view gets cached in sendEvent: before
> makeKeyAndOrderFront: gets called. We just need to move the detection 
> of
> this view a few lines down. Could you please test this, before I make
> this change?

I have tried the following:

             v = nil;// [_wv hitTest:[theEvent locationInWindow]];
              if (_f.is_key == NO && _windowLevel != NSDesktopWindowLevel)
                {
                  /* NSPanel modification: check becomesKeyOnlyIfNeeded. */
                  if (![self becomesKeyOnlyIfNeeded]
                      || [v needsPanelToBecomeKey])
                    [self makeKeyAndOrderFront: self];
                }
              v = [_wv hitTest:[theEvent locationInWindow]];
              /* Activate the app *after* making the receiver key, as app
                 activation tries to make the previous key window key. */
              if ([NSApp isActive] == NO && self != [NSApp iconWindow])
                {
                  [NSApp activateIgnoringOtherApps: YES];
                }
              if (_firstResponder != v)
                {
                 [self makeFirstResponder: v];
                }

This solves the issue. The app no longer dies. However, what do we do 
with [v needsPanelToBecomeKey]?

Regards,

  Andreas