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I have a background thread and the thread calls some methods that update the UI (in order to show progress bars and show additional info in text areas). If I modify some UI widget values, a "Cannot send events to objects owned by a different thread" assertion error is raised. Looking at forums, I read that I could use QMetaObject::invokeMethod method but it just works if I pass it the Qt::DirectConnection flag that actually raises the same error shown above. If I use Qt::QueuedConnection or Qt::AutoConnection, the invokeMethod returns false. My code looks similar to this: .h: class A : public QMainWindow { Q_OBJECT QProgressBar* pb; public slots: bool m(bool, int); }; class B { A* a; public: void handleEvent(); }; .cpp: bool A::m(bool x, int y) { pb->setValue(y); return x; } void B::handleEvent() { //a->m(true, 12); //raises an assertion error bool r; //bool ret = QMetaObject::invokeMethod(a, "m", Qt::DirectConnection, Q_RETURN_ARG(bool, r), Q_ARG(bool, true), Q_ARG(int, 12)); //raises the same assertion error error bool ret = QMetaObject::invokeMethod(a, "m", Qt::AutoConnection, Q_RETURN_ARG(bool, r), Q_ARG(bool, true), Q_ARG(int, 12)); //is ignored and ret contains false. } Do you know what is going on or what i am doing wrong? or maybe, can someone suggest me another approach to deal with my newbie problem? Thanks in advance, Ernesto

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