A roof system comprises a panel movable between closed and open positions. An operating mechanism comprises front and rear devices. A slide moves the panel both in vertical and horizontal directions via the front and rear devices. At least one of the front and rear devices comprises a lever connected to the slide or the stationary rail through a second pivot pin. A first guide cam is at least partly in engagement with either a stationary guide and/or a curve in the slide. The slide includes a first and second slide part are pivotally connected to each other. One of the slide parts, that is pivotally and slidably connected to said lever, includes a cam engaging a guide curve in the stationary guide rail to force said one slide part to pivot with respect to the other slide part during at least a part of the sliding movement of the slide.