100 % reproducable on Linux 2001041921 (without flash plugin). Going to $URL crashes my browser. I'll attach a minimized testcase ... removing anything further will prevent the crash in my experience. The content of the "type" and "classid" attributes is irrelevant, but they need to be there. Here are the dying words: [...] InstantiateEmbededPlugin.. returning Inside ns4xPluginInstance::SetWindow(0x875ea10)... About to call CallNPP_SetWindowProc()... Nullplugin: plugin received window resize. Window=(141945360) W=(240) H=(200) Falling out of ns4xPluginInstance::SetWindow()... Inside ns4xPluginInstance::SetWindow(0x875ea10)... About to create new ws_info... About to create new xtbin of 240 X 200 from 0x8799968... About to show xtbin(0x87096c8)... completed gtk_widget_show(0x87096c8) About to call CallNPP_SetWindowProc()... Falling out of ns4xPluginInstance::SetWindow()... Gdk-ERROR **: BadDrawable (invalid Pixmap or Window parameter) serial 17 error_code 9 request_code 55 minor_code 0

Most likely a recently introduced regression. Queue synchronization problem. Marking dup. *** This bug has been marked as a duplicate of 76505 ***

Indeed, both the testcase and URL work in a build including the patch from 76505.