Can't define connection type when connecting functions and/or functors

It it is not possible to define a connection type when connecting a functor/lambda or a function to a signal.
When I try this pseudocode:

// Make the status bar visible:
statusBar()->showMessage( "" );
QThread *thread = new QThread;
connect( thread, &QThread::started, [this] {
    statusBar()->showMessage( "Thread started." );
});

then the lambda is connected with Qt::DirectConnection (qobject.h, line 314) for functors and for functions (qobject.h, line 261). This results in an "QCoreApplication::sendEvent: “Cannot send events to objects owned by a different thread"
The typical solution would be to specify Qt::QueuedConnection, which is not possible with the current signature. The problem is that functors/functions don't have a thread affinity, and so it's not possible to determine what kind of event transportation mechanism should be used. But the thread affinity of functors/functions can't be changed and so it should be save to store the thread which is calling connect().

http://qt-project.org/forums/viewthread/29745/