A roof-cleaning device for moving side windows of a convertible vehicle an appropriate distance clear of a roof hinged to the vehicle body, and capable of detecting an event in or in the surroundings of the vehicle, includes: a first motion detector designed to occupy a first operational state and a second standby state, and a second detector coupled to the first detector and of lower power consumption, wherein I. with the first detector in the standby state, if the second detector detects an event to which it is sensitive, then the first detector switches into the operational state so that it can play a part in moving the window clear of the roof, II. and if, while in this operational state, the first detector detects the presence, intervention or action of the individual, then the windows are rolled down before the door is, or can be, opened.