events and form problems Slot ? Help Mainmenu for form "Widget"

Hello such I put them in context.
My problem is the next . When I run my Mainwindows.pyw from the console in order to open a new form from the menu function ok.
Now when this new form will run an event or slot example click a button performs no action and it is very strange because when I run this form is run separately example: "python3 form_new.pyw" works well its buttons "save"
As I fix step github link to download the project and see this in Spanish

https://github.com/lriccombene/PrototipoMainwindowQT5


Saludos