Windows Client crash when running in the MSVC2010 debugger. It crashed because m_scrollableArea is NULL. bool SelectorChecker::checkScrollbarPseudoClass(const SelectorCheckingContext& context, Document* document, const CSSSelector* selector) const { ... case CSSSelector::PseudoCornerPresent: >>>> return scrollbar->scrollableArea()->isScrollCornerVisible(); default: return false; } - scrollbar 0x156a4998 {m_owner={...} m_owningFrame=0x00000000 m_parts={...} } WebCore::RenderScrollbar * - WebCore::Scrollbar {m_scrollableArea=0x00000000 m_orientation=HorizontalScrollbar m_controlSize=RegularScrollbar ...} WebCore::Scrollbar + WebCore::Widget {m_parent=0x00000000 m_widget=0x00000000 m_selfVisible=false ...} WebCore::Widget + WebCore::ScrollbarThemeClient {...} WebCore::ScrollbarThemeClient + m_scrollableArea 0x00000000 {m_scrollAnimator={...} m_constrainsScrollingToContentEdge=??? m_inLiveResize=??? ...} WebCore::ScrollableArea * m_orientation HorizontalScrollbar WebCore::ScrollbarOrientation m_controlSize RegularScrollbar WebCore::ScrollbarControlSize + m_theme 0x132ed2e0 WebCore::ScrollbarTheme * m_visibleSize 0x000001a0 int m_totalSize 0x00000210 int m_currentPos 0.00000000 float m_dragOrigin 0.00000000 float m_lineStep 0x00000028 int m_pageStep 0x0000016c int m_pixelStep 1.0000000 float m_hoveredPart NoPart WebCore::ScrollbarPart m_pressedPart NoPart WebCore::ScrollbarPart m_pressedPos 0x00000000 int m_scrollPos 0.00000000 float m_draggingDocument false bool m_documentDragPos 0x00000000 int m_enabled true bool + m_scrollTimer {m_object=0x156a4998 m_function=0x02c28480 } WebCore::Timer m_overlapsResizer false bool m_suppressInvalidation false bool m_isAlphaLocked false bool + m_owner {m_ptr=0x152c6640 } WTF::RefPtr + m_owningFrame 0x00000000 {m_destructionObservers={...} m_page=??? m_treeNode={...} ...} WebCore::Frame * + m_parts {m_impl={...} } WTF::HashMap,WTF::HashTraits,WTF::HashTraits > Call Stack: > Qt5WebKitd.dll!WebCore::SelectorChecker::checkScrollbarPseudoClass(const WebCore::SelectorChecker::SelectorCheckingContext & context, WebCore::Document * document, const WebCore::CSSSelector * selector) Line 883 + 0xe bytes C++ Qt5WebKitd.dll!WebCore::SelectorChecker::checkOne(const WebCore::SelectorChecker::SelectorCheckingContext & context) Line 425 + 0x20 bytes C++ Qt5WebKitd.dll!WebCore::SelectorChecker::match(const WebCore::SelectorChecker::SelectorCheckingContext & context, WebCore::PseudoId & dynamicPseudo) Line 153 + 0xc bytes C++ Qt5WebKitd.dll!WebCore::SelectorChecker::match(const WebCore::SelectorChecker::SelectorCheckingContext & context, WebCore::PseudoId & dynamicPseudo) Line 273 + 0x10 bytes C++ Qt5WebKitd.dll!WebCore::ElementRuleCollector::ruleMatches(const WebCore::RuleData & ruleData, const WebCore::ContainerNode * scope, WebCore::PseudoId & dynamicPseudo) Line 378 + 0x10 bytes C++ Qt5WebKitd.dll!WebCore::ElementRuleCollector::doCollectMatchingRulesForList<0>(const WTF::Vector * rules, const WebCore::MatchRequest & matchRequest, WebCore::StyleResolver::RuleRange & ruleRange) Line 414 + 0x17 bytes C++ Qt5WebKitd.dll!WebCore::ElementRuleCollector::collectMatchingRulesForList(const WTF::Vector * rules, const WebCore::MatchRequest & matchRequest, WebCore::StyleResolver::RuleRange & ruleRange) Line 393 C++ Qt5WebKitd.dll!WebCore::ElementRuleCollector::collectMatchingRules(const WebCore::MatchRequest & matchRequest, WebCore::StyleResolver::RuleRange & ruleRange) Line 176 C++ Qt5WebKitd.dll!WebCore::ElementRuleCollector::matchAuthorRules(bool includeEmptyRules) Line 292 C++ Qt5WebKitd.dll!WebCore::StyleResolver::pseudoStyleForElement(WebCore::Element * e, const WebCore::PseudoStyleRequest & pseudoStyleRequest, WebCore::RenderStyle * parentStyle) Line 1156 C++ Qt5WebKitd.dll!WebCore::RenderObject::getUncachedPseudoStyle(const WebCore::PseudoStyleRequest & pseudoStyleRequest, WebCore::RenderStyle * parentStyle, WebCore::RenderStyle * ownStyle) Line 2845 + 0x26 bytes C++ Qt5WebKitd.dll!WebCore::RenderScrollbar::getScrollbarPseudoStyle(WebCore::ScrollbarPart partType, WebCore::PseudoId pseudoId) Line 154 + 0x3a bytes C++ Qt5WebKitd.dll!WebCore::RenderScrollbar::updateScrollbarPart(WebCore::ScrollbarPart partType, bool destroy) Line 227 + 0x25 bytes C++ Qt5WebKitd.dll!WebCore::RenderScrollbar::setHoveredPart(WebCore::ScrollbarPart part) Line 131 C++ Qt5WebKitd.dll!WebCore::Scrollbar::mouseExited() Line 439 C++ Qt5WebKitd.dll!WebCore::EventHandler::updateLastScrollbarUnderMouse(WebCore::Scrollbar * scrollbar, bool setLast) Line 3806 C++ Qt5WebKitd.dll!WebCore::EventHandler::handleMousePressEvent(const WebCore::PlatformMouseEvent & mouseEvent) Line 1633 C++ Qt5WebKitd.dll!QWebPageAdapter::mousePressEvent(QMouseEvent * ev) Line 510 + 0x13 bytes C++ Qt5WebKitWidgetsd.dll!QWebPage::event(QEvent * ev) Line 2473 C++ Qt5WebKitWidgetsd.dll!QWebView::mousePressEvent(QMouseEvent * ev) Line 873 C++ Qt5Widgetsd.dll!QWidget::event(QEvent * event) Line 7943 C++ Qt5WebKitWidgetsd.dll!QWebView::event(QEvent * e) Line 732 C++ Qt5Widgetsd.dll!QApplicationPrivate::notify_helper(QObject * receiver, QEvent * e) Line 3482 + 0x11 bytes C++ Qt5Widgetsd.dll!QApplication::notify(QObject * receiver, QEvent * e) Line 3016 + 0x32 bytes C++ Qt5Cored.dll!QCoreApplication::notifyInternal(QObject * receiver, QEvent * event) Line 881 + 0x15 bytes C++ Qt5Cored.dll!QCoreApplication::sendSpontaneousEvent(QObject * receiver, QEvent * event) Line 235 + 0x38 bytes C++ Qt5Widgetsd.dll!QApplicationPrivate::sendMouseEvent(QWidget * receiver, QMouseEvent * event, QWidget * alienWidget, QWidget * nativeWidget, QWidget * * buttonDown, QPointer & lastMouseReceiver, bool spontaneous) Line 2503 + 0xe bytes C++ Qt5Widgetsd.dll!QWidgetWindow::handleMouseEvent(QMouseEvent * event) Line 491 + 0x27 bytes C++ Qt5Widgetsd.dll!QWidgetWindow::event(QEvent * event) Line 174 C++ Qt5Widgetsd.dll!QApplicationPrivate::notify_helper(QObject * receiver, QEvent * e) Line 3482 + 0x11 bytes C++ Qt5Widgetsd.dll!QApplication::notify(QObject * receiver, QEvent * e) Line 2903 + 0x10 bytes C++ Qt5Cored.dll!QCoreApplication::notifyInternal(QObject * receiver, QEvent * event) Line 881 + 0x15 bytes C++ Qt5Cored.dll!QCoreApplication::sendSpontaneousEvent(QObject * receiver, QEvent * event) Line 235 + 0x38 bytes C++ Qt5Guid.dll!QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent * e) Line 1587 + 0xe bytes C++ Qt5Guid.dll!QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent * e) Line 1398 + 0x9 bytes C++ Qt5Guid.dll!QWindowSystemInterface::sendWindowSystemEvents(QFlags flags) Line 575 + 0x9 bytes C++ qwindowsd.dll!QWindowsGuiEventDispatcher::sendPostedEvents() Line 89 + 0xd bytes C++ Qt5Cored.dll!qt_internal_proc(HWND__ * hwnd, unsigned int message, unsigned int wp, long lp) Line 423 C++ user32.dll!_InternalCallWinProc@20() + 0x23 bytes user32.dll!_UserCallWinProcCheckWow@32() + 0xb7 bytes user32.dll!_DispatchMessageWorker@8() + 0xed bytes user32.dll!_DispatchMessageW@4() + 0xf bytes Qt5Cored.dll!QEventDispatcherWin32::processEvents(QFlags flags) Line 757 C++ qwindowsd.dll!QWindowsGuiEventDispatcher::processEvents(QFlags flags) Line 80 + 0xd bytes C++ Qt5Cored.dll!QEventLoop::processEvents(QFlags flags) Line 137 C++ Qt5Cored.dll!QEventLoop::exec(QFlags flags) Line 212 + 0x26 bytes C++ Qt5Cored.dll!QCoreApplication::exec() Line 1134 + 0x15 bytes C++ Qt5Guid.dll!QGuiApplication::exec() Line 1333 C++ Qt5Widgetsd.dll!QApplication::exec() Line 2708 C++ Media Director Drop Utility.exe!main(int argc, char * * argv) Line 74 C++ Media Director Drop Utility.exe!WinMain(HINSTANCE__ * instance, HINSTANCE__ * prevInstance, char * __formal, int cmdShow) Line 131 + 0x12 bytes C++ Media Director Drop Utility.exe!__tmainCRTStartup() Line 547 + 0x2c bytes C Media Director Drop Utility.exe!WinMainCRTStartup() Line 371 C kernel32.dll!@BaseThreadInitThunk@12() + 0x12 bytes ntdll.dll!___RtlUserThreadStart@8() + 0x27 bytes ntdll.dll!__RtlUserThreadStart@8() + 0x1b bytes