This crash took me about 40hr+ to replicate and find a way how to eliminate it (unfortunately not to fix it). This crash occurred only on OS X 10.10, not 10.9, not Linux, not Windows.
Bug occurred in slightly modified QtTreePropertyBrowser where we have additional buttons for each property.
When any of these buttons caused property tree refresh, application randomly crashed. But when these actions were executed by buttons outside of the property tree, everything worked fine.
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread 0 org.qt-project.QtWidgets 0x0000000103f49290 QTreeModel::index(QTreeWidgetItem const*, int) const + 176 1 org.qt-project.QtWidgets 0x0000000103f4950b QTreeModel::parent(QModelIndex const&) const + 75 2 org.qt-project.QtWidgets 0x0000000103f23bb7 QTreeView::isIndexHidden(QModelIndex const&) const + 71 3 org.qt-project.QtWidgets 0x0000000103f17e0d QTreeView::visualRect(QModelIndex const&) const + 93 4 org.qt-project.QtWidgets 0x0000000103ec490d QAccessibleTableCell::rect() const + 29 5 org.qt-project.QtWidgets 0x0000000103ec46f2 QAccessibleTableCell::state() const + 146 6 libqcocoa.dylib 0x00000001071913aa QCocoaAccessible::hasValueAttribute(QAccessibleInterface*) + 58 7 libqcocoa.dylib 0x000000010718df7e -[QMacAccessibilityElement accessibilityAttributeNames] + 398 8 com.apple.AppKit 0x00007fff95dea26e NSAccessibilityEntryPointAttributeNames + 115 9 com.apple.AppKit 0x00007fff95e275af -[NSObject(NSAccessibilityInternal) _accessibilityAttributeNamesClientError:] + 56 10 com.apple.AppKit 0x00007fff95e2a62a CopyAttributeNames + 216 11 com.apple.HIServices 0x00007fff9768cbce _AXXMIGCopyAttributeNames + 252 12 com.apple.HIServices 0x00007fff976950c6 _XCopyAttributeNames + 385 13 com.apple.HIServices 0x00007fff97671109 mshMIGPerform + 199 14 com.apple.CoreFoundation 0x00007fff99259c79 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 41 15 com.apple.CoreFoundation 0x00007fff99259beb __CFRunLoopDoSource1 + 475 16 com.apple.CoreFoundation 0x00007fff9924b767 __CFRunLoopRun + 2375 17 com.apple.CoreFoundation 0x00007fff9924abd8 CFRunLoopRunSpecific + 296 18 com.apple.HIToolbox 0x00007fff9695d56f RunCurrentEventLoopInMode + 235 19 com.apple.HIToolbox 0x00007fff9695d2ea ReceiveNextEventCommon + 431 20 com.apple.HIToolbox 0x00007fff9695d12b _BlockUntilNextEventMatchingListInModeWithFilter + 71 21 com.apple.AppKit 0x00007fff95a489bb _DPSNextEvent + 978 22 com.apple.AppKit 0x00007fff95a47f68 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 346 23 libqcocoa.dylib 0x000000010717b29d QCocoaEventDispatcher::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) + 2093 24 org.qt-project.QtCore 0x0000000104b0337d QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) + 381 25 org.qt-project.QtWidgets 0x0000000103e6c192 QDialog::exec() + 514
I updated methods from signals-slots mechanism to QEvent system. Unfortunately this didn’t help as well. Next attempt was QTimer usage instead of QEvent or signal-slot to simulate real click. But also without any success.
0 org.qt-project.QtWidgets 0x000000011112f62e QTreeModel::data(QModelIndex const&, int) const + 46 1 org.qt-project.QtWidgets 0x00000001110aa7bb QAccessibleTableCell::state() const + 347 2 libqcocoa.dylib 0x00000001143913aa QCocoaAccessible::hasValueAttribute(QAccessibleInterface*) + 58 3 libqcocoa.dylib 0x000000011438df7e -[QMacAccessibilityElement accessibilityAttributeNames] + 398 4 com.apple.AppKit 0x00007fff95dea26e NSAccessibilityEntryPointAttributeNames + 115 5 com.apple.AppKit 0x00007fff95e275af -[NSObject(NSAccessibilityInternal) _accessibilityAttributeNamesClientError:] + 56
With a lot of luck I finally found the reason for the crash. It’s caused by erasing a property tree (and inner QTreeWidget) together with an active focus on this widget. Unfortunately I’m not able to fix it in the QtCore because according to callstack there is only some QModelIndex manipulation without any sight of what’s going wrong.
The effective solution how to fix this wrong behaviour is to temporally set focus to another widget (or parent), clear the tree and set focus back to property tree. Unfortunately this solution doesn’t work. Check part II of this article for better solution
QWidget* pObject = qobject_cast<QWidget*>(m_propertyBrowser->parent());
if (pObject!=NULL);
pObject->setFocus();
m_propertyBrowser->clear();
m_propertyBrowser->setFocus();
If anyone know how to fix that, I will be glad for any info.
