"Save Changes" option when closing the app.

[martijnvanschie]

• [x] I agree to follow the Code of Conduct that this project adheres to.
• [x] I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Describe the solution you'd like When closing a diagram which is unsaved you get a confirmation dialog telling the user the document has unsaved changes. It then only provides an option to Discard Changes. It would be helpful if the dialog allowed the user to also choose Save Changes.

Describe alternatives you've considered An option that allowed the user to specify Save on closing app, or an option to continuedly save the document on changes.