A roller shutter for an opening leaf of a building, includes a retractable shut-off panel that moves between retracted and deployed positions, and a guide to selectively guide the panel a path between the retracted position and a deployed position in a first plane, and another path is a path between the retracted position and a deployed position in a second plane parallel to said first plane. The guide selectively switches movement of between said first path and said second path. A deployment-switching stop guides the shut-off panel along the second path when the shut-off panel is in contact with the deployment switching stop and the shaft is driven in a direction of rotation for deployment.