A screening arrangement for a roof window to be installed in an inclined or flat roof of a building to cover an opening of the window in a mounted condition of the screening arrangement, where the screening arrangement comprises: a screening device including a top casing, a screening body having two side edges, a first end portion and a second end portion, said screening body being movable in a longitudinal direction between a non-screening position, in which the screening body is substantially accommodated in the top casing, and a number of screening positions in which the screening body is deployed from the top casing and covers the opening partially or entirely, two side rails (63, 64) configured to extend substantially perpendicularly to the top casing in a mounted condition of the screening arrangement, the top casing and the two side rails (63, 64) defining an outer perimeter of the screening device, and a roller bar accommodated in the top casing and connected to drive means, the drive means being configured to rotate the roller bar in a winding direction and an unwinding direction, the first end portion of the screening body being connected to the roller bar such that the screening body is wound on the roller bar in the non-screening position, and wherein the roller bar extends longitudinally between a first longitudinal end (61r1) and a second longitudinal end (61r2), the top casing comprising a bottom element and a top element delimiting a bar space accommodating and limiting movement of the roller bar, characterised in that the screening arrangement comprises a winding device comprising at least one winding reel in connection with or connectable to the roller bar at the first longitudinal end (61r1) of the roller bar, that the top casing comprises a bottom end element and a top end element adjacent to the first longitudinal end (61r1) of the roller bar and further delimiting the bar space, the bottom end element and the top end element delimiting a reel space accommodating and limiting movement of the at least one winding reel, and that the bottom element of the top casing is configured to receive and support the roller bar during assembly of the screening arrangement and the top element is configured to be connected to the bottom element subsequent to the bottom element receiving the roller bar. a screening device including a top casing, a screening body having two side edges, a first end portion and a second end portion, said screening body being movable in a longitudinal direction between a non-screening position, in which the screening body is substantially accommodated in the top casing, and a number of screening positions in which the screening body is deployed from the top casing and covers the opening partially or entirely, two side rails (63, 64) configured to extend substantially perpendicularly to the top casing in a mounted condition of the screening arrangement, the top casing and the two side rails (63, 64) defining an outer perimeter of the screening device, and a roller bar accommodated in the top casing and connected to drive means, the drive means being configured to rotate the roller bar in a winding direction and an unwinding direction, the first end portion of the screening body being connected to the roller bar such that the screening body is wound on the roller bar in the non-screening position, and wherein the roller bar extends longitudinally between a first longitudinal end (61r1) and a second longitudinal end (61r2), the top casing comprising a bottom element and a top element delimiting a bar space accommodating and limiting movement of the roller bar, characterised in that the screening arrangement comprises a winding device comprising at least one winding reel in connection with or connectable to the roller bar at the first longitudinal end (61r1) of the roller bar, that the top casing comprises a bottom end element and a top end element adjacent to the first longitudinal end (61r1) of the roller bar and further delimiting the bar space, the bottom end element and the top end element delimiting a reel space accommodating and limiting movement of the at least one winding reel, and that the bottom element of the top casing is configured to receive and support the roller bar during assembly of the screening arrangement and the top element is configured to be connected to the bottom element subsequent to the bottom element receiving the roller bar.