BUG #14029: Fix Plot3D panel.

Multivalued enumeration properties were not handled correctly. This fix
addresses that issue.

Change-Id: I47a6b7bce053bbd2a36564c6ee19f38f0754dbff
Merge topic 'refactor_panels' into next

c9230f4 BUG #14029: Fix Plot3D panel.
Fix debugging message.

Change-Id: I62d95129ec288c831e848c43e098db9ccaac3b81
Merge topic 'refactor_panels' into next

46a3b0c Fix debugging message.