Re: Can I use gtk_widget_unref() to releasetthe object created by gtk_invisible_new()?

[Brian Lu <Brian.Lu@xxxxxxx>]

Thanks a lot for your explanation.  But look at following snippet from 
firefox latest code base:
    void InitWidget() {
        mWidget = gtk_invisible_new();
        gtk_object_ref(GTK_OBJECT(mWidget));
        gtk_object_sink(GTK_OBJECT(mWidget));
        gtk_widget_ensure_style(mWidget);
        mStyle = gtk_widget_get_style(mWidget);
    }
see 
http://lxr.mozilla.org/seamonkey/source/widget/src/gtk2/nsLookAndFeel.h#77
and
nsLookAndFeel::~nsLookAndFeel()
{
    //  gtk_widget_destroy(mWidget);
    gtk_widget_unref(mWidget);
}
see 
http://lxr.mozilla.org/seamonkey/source/widget/src/gtk2/nsLookAndFeel.cpp#78

I find mWidget is leaked (detected by using libumem.so provided by solaris).

I don't understand why calling gtk_object_ref() to increase mWidget 
reference count. 
This causes mWidget's reference count to be 2 and gtk_widget_unref() in 
deconstructor decreases it to 1.

Thanks

Brian



Markku Vire wrote:
> Hi,
>
> The caller doesn't own the returned reference in case of any gtk_*_new
> functions, but the results are floating references (they are removed
> once somebody calls gtk_object_sink). This is different from normal
> GObjects. So, unreffing the returned value causes practically a double
> free.
>
> gtk_widget_destroy in turn runs dispose, ie. asks widget to drop
> references to other widgets. Dropping external references usually causes
> somebody else to drop the last reference to your widget, so it
> efectively gets destroyed. In case of toplevels some global window list
> is holding the reference.
>
> Calling gtk_widget_destroy without taking ownership a a widget is
> usually a bug that causes a memory leak, but this is not the case here,
> since we are talking about a toplevel.
>
> Cheers,
>
> -Markku- 
>
> On Wed, 2008-01-09 at 17:39 +0800, Brian Lu wrote:
>   
>> Hi, experts,
>>
>> I found following codes will crash in gnome 2.21 environment:
>>
>>   ...
>>   GtkWidget *foo = gtk_invisible_new();
>>   gtk_widget_unref(foo);
>>   ...
>>
>> But it works well if gtk_widget_unref() is replaced with 
>> gtk_widget_destroy().
>>
>> Does that mean that we can't use gtk_widget_unref() on such object and 
>> we can only
>> use gtk_widget_destroy() to release it?
>>
>> Thanks
>>
>> Brian
>> _______________________________________________
>> gtk-devel-list mailing list
>> gtk-devel-list@xxxxxxxxx
>> http://mail.gnome.org/mailman/listinfo/gtk-devel-list
>>     
>
>   

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