Re: QwtPlotPicker event recursion

[Dave F. <dfl...@ak...>]

Hi Uwe:

It seems you came to the same conclusion without my "extra" information.


It does seem that on OSX you can get these QEvent::Leave events from the Qt 
main event handler, if the X11 implementation issues a XFocus event (which in 
turn may be happening as a result of something Qt does when we call hide().)

We have applied your patch here for testing on our OSX test box (and mac users 
machines).  So far so good. We'll monitor it and I'll let you know if that 
crash occurs again (I'm pretty sure it will not).

Thanks for the help,
Dave



On Tuesday 23 March 2010 15:43:00 Uwe Rathmann wrote:
> > Occasionally, on application startup it will segfault. From the stack
> > trace it looks like the QwtPicker::PickerWidget object's constructor is
> > recursively triggering an update() event which is causing a a new
> > PickerWidget to be created, etc. etc. until the stack depth causes the
> > segfault (at depth of 512 on OSX)
> 
> I'm not 100% sure about your stack as there is a call of updateDisplay in
> eventFilter, that I can't see in the code. Also the situation looks like
> nobody could ever used a picker ( = zoomer ) on the Mac.
> 
> Anyway it looks like the hide() in the constructur of the PickerWidget
>  causes an Enter or LeaveEvent, that is triggering the recursive
>  updateDisplay. Maybe this event is only sent under certain circumstances.
> 
> I simply moved the hide() to outside of the constructor - available in the
>  SVN 5.2 branch.
> 
> Uwe
> 
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