The hover text on a derived column said only that the column cannot be edited, which tells the user nothing about what it holds. It now carries the column label - the configured VAR_LABEL, or the generated name=expression that mp_derivedvars writes when the administrator left the label blank - and falls back to the plain rule when the label merely repeats the column name. The cypress case that marks derived columns apart now also checks the tooltip for both shapes: REGION_LABEL carries a configured label, REGION falls back to the generated one.