The window comprises a frame with a top member (6), a bottom member (7) and two side members (4, 5), which are connected with each other in corner joints, and a plurality of mounting brackets (10). The side members and the top and bottom members of the frame in the mounted position of the window extend essentially parallel to rafter (2) and batten (3, 8, 9) elements, respectively, in the roof structure. Each mounting bracket (10) comprises a first leg portion (11) for connection with an associated frame member and a second leg portion (12) which is essentially perpendicular to the first leg portion and is to be fastened to the roof structure, each mounting bracket being designed as a gusset where the first leg portion (11) is designed as two leg sections (11a, 11b) essentially perpendicular to each other for connection with adjacent frame members at the joint between these.