In fact, responding with mouse events does not requires the use of SIGNAL/SLOT mechanism.

I dont know Python but in C++, you need to derived your widget and reimplement the method QWidget::mousePressEvent(QMouseEvent).
Be aware of QEvent derived argument .

Then, you are free to emit other signals for your own design.

In the sample you provided, I notice that :
* you emit a signal in response of pressEvent but why not direclty call the function you want to be executed
* the arguments between the signal you emitted and the slot you have connected to it dont match. It cant work. Don't you have any warnings somewhere about failed connect?