UI for polygons with inner rings is confusing for beginners

[olivierdalang]

Hi !

Another small problem I have with the app is the UI to create inner rings in polygons. It's well thought and works very well, but here users are tending to mix up the creation of another polygon with the creation of a new ring.

The users click on add a ring, thinking they add a polygon, of course they draw the ring outside of the original polygon, and get the error "One of the holes outside of the outer ring", which is explicit for GIS veterans but a bit cryptic for a beginner.

It would be great if there was a setting (either general, or per layer) to simply hide the inner rings buttons from the UI. Maybe the buttons would be always shown if the features already has rings, just to avoid being unable to delete existing rings.

Best regards,

Olivier