I currently am designing a settings/configuration menu and some of these pages have required fields. When the user leaves a required field empty, what should be the expected behavior when moving to a different menu? For example, in the image one of the required fields are empty. If the user wants to move to menu 1 while the required field is still invalid, should the user be allows to move menus?
I have considered preventing the user from leaving the page by having a "warning" pop up and telling them that they need to complete all mandatory fields before continuing. I also considered having a pop up that gives the user a warning that all mandatory fields must be completed, but if they wish to continue than all their changes will revert to the original. What is the better option? Is there another alternative?