Created attachment 255638 [details] full backtrace I'm not really sure what to make of this crash report, whether it's a WebKit issue or an X11 issue: Truncated backtrace: Thread no. 1 (10 frames) #0 XQueryExtension at QuExt.c:43 #1 XInitExtension at InitExt.c:47 #2 XDamageExtAddDisplay at Xdamage.c:58 #3 XDamageFindDisplay at Xdamage.c:202 #4 XDamageQueryExtension at Xdamage.c:288 #5 WebKit::supportsXDamageAndXComposite at /usr/src/debug/webkitgtk-2.9.3/Source/WebKit2/UIProcess/gtk/RedirectedXCompositeWindow.cpp:115 #6 WebKit::RedirectedXCompositeWindow::create(_GdkWindow*, std::function<void ()>) at /usr/src/debug/webkitgtk-2.9.3/Source/WebKit2/UIProcess/gtk/RedirectedXCompositeWindow.cpp:135 #7 webkitWebViewBaseRealize at /usr/src/debug/webkitgtk-2.9.3/Source/WebKit2/UIProcess/API/gtk/WebKitWebViewBase.cpp:332 #12 gtk_widget_realize at gtkwidget.c:5551 #13 gtk_widget_map at gtkwidget.c:5066 QuExt.c is pretty simple [1]; looks like we may have passed an invalid display (dpy=dpy@entry=0x55c3119500b0). [1] http://cgit.freedesktop.org/xorg/lib/libX11/tree/src/QuExt.c
Hrm. We are just calling gdk_window_get_display on the GdkWindow returned from gtk_widget_get_parent_window in the realize method of the widget.