Thanks for the response!

What about through QProcess or another Qt Class? I could work with the connect() function but would need to find a way to get a pointer to the running app?

Is it possible to get some kind of QObject (or other) pointer to a running Qt app, say, if it was launched using QProcess??

for example, are there any methods through QProcess (or other class) that would do:

CMyMainWindowClass::CMyMainWindowClass(){
. . .

m_myProcess = new QProcess(this);
m_myProcess->start("myoldQtapp.exe", arguments);

QObject *obj = m_myProcess->GetQtObjectPointerToApp(); //how could I get the running app's QObject or QMainWindow pointer for connecting Slots to??

connect(obj, SIGNAL(oldappsignal()), this, SLOT(OnOldAppSignal()));
}