Steps to reproduce

1. Log in to Magnolia author as superuser 
2.  Open the pages app and create a new page using the Basic Template.
3. Save changes
4. Click to select the page and when highlighted, click "Change Template"
5. Select a template that includes mandatory fields
6. Save
7. Notice that the template is immediately changed and the author is not prompted to fill in the mandatory fields on the new templates properties dialog.

.. Logs, screenshots, gifs...

Expected results

The author is immediately presented with the page properties dialog for the chosen template and is alerted to the mandatory fields. Cancelling out of this dialog should not change the template but revert to the original one.

Actual results

The template is changed immediately without any warning given to the author that there are mandatory fields that need to be filled in.

Workaround

Manually open the new templates properties to fill the fields in.

Development notes