@errolflynn You should write self.button1.clicked.connect(ft_handler) - this will register the function ft_handler as a slot for the clicked signal. On http://doc.qt.io/qt-5/qabstractbutton.html you see that the signature of that signal is void clicked(bool checked). In other words, when the signal is activated, your handler is called as ft_handler(checked) where checked is either True or False. Per the signature of the clicked signal, this is the only information you will get out of the signal.
If you want to pass additional parameters, you indeed will need to create a separate function that encodes those extra parameters and passes them to the handler. In Python it makes a lot of sense to use a lambda for it, for instance:
self.button1.clicked.connect(lambda checked: fct_handler(par1, par2, par3, checked))
Hope this helps
