Am baffled. My RoundCube front page has for a long time had three columns (folders, sender and message) and suddenly it has changed to two. The folders column is no longer showing.

How can I revert to original layout?

Tony Berry,

Author and accredited editor (IPEd);
Advanced member Chartered Institute of Editing and Proofreading;
Diploma Professional Writing & Editing;
Member Australian Society of Authors.