A modal has currently the following ways to be closed:

1. Click on the X in the top right
2. Click anywhere outside the modal
3. Push the Escape key
4. Successfully submit a form
5. Click on the cancel button (Show a cancel button in modals #5305)

Cases 2 and 3 can easily be triggered, without any intention of the user to close the modal.

To prevent this, once a form has been adjusted, both cases shouldn't allow to close the modal anymore.

An alternative would be to ask for confirmation. Though, I'd like to avoid this at all cost.