FileMaker Pro & Advanced 18.104.22.168
Mac OS Sierra 10.12.2
Various computer hardware
On a layout portal where "Allow deletion of portal records" is unchecked, a user can click on a portal row, then hit the delete key on the keyboard, and get a dialog to delete the portal row. The suppression of the allow deletion is ignored.
In this case, the portal row is a button with a single step that sets a field in the parent record to the primary key for the related record to display data. So the user cannot click IN the portal row, but if they click the button and then immediately hit the delete key, they get the dialog. Clicking delete in the dialog does delete the portal row.
A test on portal rows where the user can click in a field found the suppression works correctly in that instance.
Workaround: I am replacing the single step with a script that sets that field and then commits the record so that focus is lost.