Call functions from another classes

[Julio CamPlaz]

Hello,

I´m making a little example and there is a thing I do not undestand. I created a TabPannel with 3 initial tabs, and I created two botons which add a new tab when you press them. The second one adds the tab directly and it works perfectly.The first one opens a Popup in order to be able to put the name to the new tab, however, the button "OK" (inside the Popup widget does not work).

I created two classes: the MainWindow class, and the Popup class.

The question is: HOW CAN I CALL A MAINWINDOW CLASS FUNCTION FROM THE POPUP CLASS???

 If I do..

on_press: MainWindow().shown()  ----> it raises this error: NameError: name 'MainWindow' is not defined.

I have done it from several ways and I does not work...

How can I do it?? Thanks you!!

I show the code in the following picture:

[Alexander Taylor]

If a MainWindow instance is the root widget, use app.root.shown(). You can't do root.shown() because root refers to the root of the kv rule, not the root of the whole application.