I am using QtWebkit 5.1.0 on Windows 7. When I enter some Chinese text via Google Chinese Pinyin IME into the search box on Google homepage, every now and then, webkit crashes due to the following assert: bool Node::isFocusable() const { if (!inDocument() || !supportsFocus()) return false; // Elements in canvas fallback content are not rendered, but they are allowed to be // focusable as long as their canvas is displayed and visible. if (isElementNode() && toElement(this)->isInCanvasSubtree()) { const Element* e = toElement(this); while (e && !e->hasLocalName(canvasTag)) e = e->parentElement(); ASSERT(e); return e->renderer() && e->renderer()->style()->visibility() == VISIBLE; } if (renderer()) ------> ASSERT(!renderer()->needsLayout()); else // If the node is in a display:none tree it might say it needs style recalc but // the whole document is actually up to date. ASSERT(!document()->childNeedsStyleRecalc()); // FIXME: Even if we are not visible, we might have a child that is visible. // Hyatt wants to fix that some day with a "has visible content" flag or the like. if (!renderer() || renderer()->style()->visibility() != VISIBLE) return false; return true; } Here is entire stack: ntdll.dll!_ZwRaiseException@12() + 0x12 bytes ntdll.dll!_ZwRaiseException@12() + 0x12 bytes > Qt5WebKitd.dll!WebCore::Node::isFocusable() Line 927 + 0x3c bytes C++ Qt5WebKitd.dll!WebCore::HTMLFormControlElement::isFocusable() Line 330 C++ Qt5WebKitd.dll!WebCore::HTMLInputElement::isTextFormControlFocusable() Line 398 C++ Qt5WebKitd.dll!WebCore::TextFieldInputType::isMouseFocusable() Line 79 C++ Qt5WebKitd.dll!WebCore::HTMLInputElement::isMouseFocusable() Line 393 C++ Qt5WebKitd.dll!WebCore::FrameSelection::setFocusedNodeIfNeeded() Line 1884 + 0x16 bytes C++ Qt5WebKitd.dll!WebCore::FrameSelection::setSelection(const WebCore::VisibleSelection & newSelection={...}, unsigned int options=0, WebCore::FrameSelection::CursorAlignOnScroll align=AlignCursorOnScrollIfNeeded, WebCore::TextGranularity granularity=CharacterGranularity) Line 298 C++ Qt5WebKitd.dll!WebCore::Editor::selectComposition() Line 1321 C++ Qt5WebKitd.dll!WebCore::Editor::setComposition(const WTF::String & text={...}, const WTF::Vector<WebCore::CompositionUnderline,0> & underlines={...}, unsigned int selectionStart=0, unsigned int selectionEnd=0) Line 1400 C++ Qt5WebKitd.dll!QWebPageAdapter::inputMethodEvent(QInputMethodEvent * ev=0x16dd2220) Line 710 + 0x2c bytes C++ Qt5WebKitWidgetsd.dll!QWebPage::event(QEvent * ev=0x16dd2220) Line 2543 C++ MyApp.exe!WebPage::event(QEvent * e=0x16dd2220) Line 1021 C++ Qt5WebKitWidgetsd.dll!QWebView::inputMethodEvent(QInputMethodEvent * e=0x16dd2220) Line 1031 C++ Qt5Widgetsd.dll!QWidget::event(QEvent * event=0x16dd2220) Line 7951 C++ Qt5WebKitWidgetsd.dll!QWebView::event(QEvent * e=0x16dd2220) Line 734 C++ Qt5Widgetsd.dll!QApplicationPrivate::notify_helper(QObject * receiver=0x0d5daa08, QEvent * e=0x16dd2220) Line 3455 + 0x11 bytes C++ Qt5Widgetsd.dll!QApplication::notify(QObject * receiver=0x0d5daa08, QEvent * e=0x16dd2220) Line 3420 + 0x10 bytes C++ Qt5Cored.dll!QCoreApplication::notifyInternal(QObject * receiver=0x0d5daa08, QEvent * event=0x16dd2220) Line 871 + 0x15 bytes C++ Qt5Cored.dll!QCoreApplication::sendEvent(QObject * receiver=0x0d5daa08, QEvent * event=0x16dd2220) Line 232 + 0x39 bytes C++ qwindowsd.dll!QWindowsInputContext::composition(HWND__ * hwnd=0x00311056, long lParamIn=184) Line 443 + 0x13 bytes C++ qwindowsd.dll!QWindowsContext::windowsProc(HWND__ * hwnd=0x00311056, unsigned int message=271, QtWindows::WindowsEventType et=InputMethodCompositionEvent, unsigned int wParam=0, long lParam=184, long * result=0x0025d9a8) Line 736 + 0x14 bytes C++ qwindowsd.dll!qWindowsWndProc(HWND__ * hwnd=0x00311056, unsigned int message=271, unsigned int wParam=0, long lParam=184) Line 951 + 0x24 bytes 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<enum QEventLoop::ProcessEventsFlag> flags={...}) Line 752 C++ qwindowsd.dll!QWindowsGuiEventDispatcher::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags={...}) Line 78 + 0xd bytes C++ Qt5Cored.dll!QEventLoop::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags={...}) Line 137 C++ Qt5Cored.dll!QEventLoop::exec(QFlags<enum QEventLoop::ProcessEventsFlag> flags={...}) Line 212 + 0x26 bytes C++ Qt5Cored.dll!QCoreApplication::exec() Line 1124 + 0x15 bytes C++ Qt5Guid.dll!QGuiApplication::exec() Line 1197 C++ Qt5Widgetsd.dll!QApplication::exec() Line 2690 C++