A window shade arrangement having a manually operated window shade web whose movement between open and closed positions is guided by guide rails at each side. A pull rode having oblong sliding blocks travels in the two guide rails. The sliding blocks, together with the pull rod, can swivel about an axis parallel to the pull rod. In this way, the sliding blocks can become secured in corresponding locking pockets in the guide rails. The locking can be released by manual turning of the pull rod in the opposite direction.