[KDE/Mac] Review Request 124061: [OS X] avoid crashing KNode when unsubscribing from a group

[Daniel Vrátil]

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Ship it!


Looks sensible, and if it fixes the crash, ship it!


knode/kncollectionview.cpp (line 180)
<https://git.reviewboard.kde.org/r/124061/#comment55758>

    Maybe add a comment why this is needed


- Daniel Vrátil


On June 10, 2015, 2:37 p.m., René J.V. Bertin wrote:
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> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/124061/
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> (Updated June 10, 2015, 2:37 p.m.)
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> 
> Review request for KDE Software on Mac OS X and KDEPIM.
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> Repository: kdepim
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> Description
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> On OS X, unsubscribing from a group with the context menu's action item (right-click on group, unsubscribe) leads to a crash systematically. Analysis of the (huge) backtrace shows that this is because a (pending?) redraw event is sent (by `qApp->processEvents()` in `KNMainWidget::secureProcessEvents`) to the group entry after it has already been deleted. (The pending event is likely to be an expose event queued when the context menu closed.)
> Normally one would avoid this situation by using `deleteLater()` instead of the direct `delete`, but since `KNCollectionViewItem` does not inherit `QObject` a workaround is needed.
> The attached patch implements a solution that to prevents the crashing in my testing. It disables the item to be removed in addition to setting it hidden, then updates the list (`setListItem(0)`), group and calls `qApp->processEvents()` explicitly before it is called in `KNMainWidget::secureProcessEvents()` so that pending events are processed first. The item is deleted only after those steps.
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> I decided not to make this modification specific to OS X (`Q_OS_MAC`) because it should not have undesirable side-effects elsewhere (and there may be other platforms where similar pending-events occur).
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> Diffs
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>   knode/kncollectionview.cpp f8bce14 
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> Diff: https://git.reviewboard.kde.org/r/124061/diff/
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> Testing
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> On Mac OS X 10.9.5 with KDELibs 4.14.7 and kdepim 4.13.3 (the patched function has not changed since that version).
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> Thanks,
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> René J.V. Bertin
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