Abstract: A blind with vertical slats has a horizontal rail for a row of trolleys which carry connectors for the upper end portions of slats and further constitute or form part of holders for the upper portion of a curtain. This ensures that the gaps between neighboring slats are bridged by the curtain when the slats are oriented in such a way that they permit light to pass between them. In addition, the curtain can be used to prevent penetration of any light, or excessive amounts of light, into or from a room when the slats are detached from their trolleys for the purpose of inspection, cleaning or replacement. The marginal portion of the curtain can carry or constitute a strip of velvety material which can strongly adhere to the barbs of one or more strips of "VELCRO" (trademark) or a like material which reliably secures the curtain to the connectors for the upper end portions of the slats.