<?xml version="1.0"?> <!-- ###!!! ASSERTION: You can't dereference a NULL nsCOMPtr with operator->().: 'mRawPtr != 0', file ../../../../dist/include/nsCOMPtr.h, line 796 Program received signal SIGSEGV, Segmentation fault. 0xb6b7463a in nsTreeContentView::SetTree (this=0xb0ba2510, aTree=0xaaecece0) at layout/xul/base/src/tree/src/nsTreeContentView.cpp:571 571 boxObject->GetElement(getter_AddRefs(element)); (gdb) bt 3 #0 0xb6b7463a in nsTreeContentView::SetTree (this=0xb0ba2510, aTree=0xaaecece0) at layout/xul/base/src/tree/src/nsTreeContentView.cpp:571 #1 0xb736c76f in NS_InvokeByIndex_P () at xpcom/reflect/xptcall/md/unix/xptcinvoke_gcc_x86_unix.cpp:69 #2 0xb6171901 in XPCWrappedNative::CallMethod (ccx=..., mode=XPCWrappedNative::CALL_METHOD) at js/src/xpconnect/src/xpcwrappednative.cpp:2722 (More stack frames follow...) (gdb) list 566 561 nsTreeContentView::SetTree(nsITreeBoxObject* aTree) 562 { 563 ClearRows(); 564 565 mBoxObject = aTree; 566 567 if (aTree && !mRoot) { 568 // Get our root element 569 nsCOMPtr<nsIBoxObject> boxObject = do_QueryInterface(mBoxObject); 570 nsCOMPtr<nsIDOMElement> element; 571 boxObject->GetElement(getter_AddRefs(element)); (gdb) p boxObject $16 = {mRawPtr = 0x0} |aTree| does not implement |nsIBoxObject|, so |do_QueryInterface(mBoxObject)| returns null. Then we have |null->GetElement()|. --> <window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="document.getElementById('tree').view.setTree({});"> <tree id="tree"> <treechildren/> </tree> </window>