A screening arrangement for a window, preferably a roof window, comprising a frame with a top member, a bottom member and two side members, the screening arrangement comprising: at least one bottom element, and two side rails defining a longitudinal direction, a width direction and a depth direction, the at least one bottom element being movable with respect to the two side rails between a non-screening position and a screening position by means of a drive means comprising a first transmission means comprising a circular gear including at least one pinion arranged in said at least one bottom element, and a second transmission means comprising two racks of teeth (20a, 20b) arranged in each of the two side rails such as to extend substantially in the longitudinal direction of the side rail, to engage with the at least one pinion of the first transmission means, each side rail comprising a first flange extending substantially in the width direction, a second flange extending substantially in parallel with the first flange, in the width direction, and positioned to cover at least a part of the bottom element, and a third flange connecting the first and second flanges (11, 12) and extending substantially in the depth direction, characterised in that said second transmission means is formed integrally in at least one of said flanges (11, 12, 13) of said side rail, and said side rail is of an extrudable material, wherein the second transmission means comprising the at least two racks of teeth (20a, 20b) to engage with the at least one pinion of the first transmission means, and wherein the teeth of said racks (20a, 20b) have a base portion provided at the at least one flange (11, 12, 13), a head portion engaging the first transmission means, and a body portion extending between the base portion and the head portion, and wherein said at least two racks (20a, 20b) are formed integrally in the same flange, and said at least two racks (20a, 20b) being preferably substantially parallel with each other, and wherein said pinion is provided with such a width that the at least one pinion extends across and is configured to mesh with at least a part of each of the two parallel racks of teeth (20a, 20b). at least one bottom element, and two side rails defining a longitudinal direction, a width direction and a depth direction, the at least one bottom element being movable with respect to the two side rails between a non-screening position and a screening position by means of a drive means comprising a first transmission means comprising a circular gear including at least one pinion arranged in said at least one bottom element, and a second transmission means comprising two racks of teeth (20a, 20b) arranged in each of the two side rails such as to extend substantially in the longitudinal direction of the side rail, to engage with the at least one pinion of the first transmission means, each side rail comprising a first flange extending substantially in the width direction, a second flange extending substantially in parallel with the first flange, in the width direction, and positioned to cover at least a part of the bottom element, and a third flange connecting the first and second flanges (11, 12) and extending substantially in the depth direction, characterised in that said second transmission means is formed integrally in at least one of said flanges (11, 12, 13) of said side rail, and said side rail is of an extrudable material, wherein the second transmission means comprising the at least two racks of teeth (20a, 20b) to engage with the at least one pinion of the first transmission means, and wherein the teeth of said racks (20a, 20b) have a base portion provided at the at least one flange (11, 12, 13), a head portion engaging the first transmission means, and a body portion extending between the base portion and the head portion, and wherein said at least two racks (20a, 20b) are formed integrally in the same flange, and said at least two racks (20a, 20b) being preferably substantially parallel with each other, and wherein said pinion is provided with such a width that the at least one pinion extends across and is configured to mesh with at least a part of each of the two parallel racks of teeth (20a, 20b).