QMetaObject::invokeMethod, call from main->slot to MainWindow->slot how i can do it?

[Ginsengelf]

Hi, first of all your MainWindow is a local variable in main(), so accessing it from another function is not possible. To fix that you could change it into a global pointer.
Second, assuming that the MainWindow variable is accessible: what about a simple function call, e.g. w->myMessageOutput_2() instead of the invokeMethod() call?

Ginsengelf