third rod 22 and the fourth rod 24 shown in dotted line form in fig3 inserted through the second retainer slot 51 b are sixth and seventh rods 36 and 38 also shown in dotted line form in fig3 the sixth and seventh rods 36 38 are respectively coupled to adjacent upper and lower curtains 32 and 34 which are not shown in fig3 for simplicity but are shown in fig1 and 2 each of the aforementioned rods is freely movable within its associated retainer slot as the upper and lower curtains are displaced upwardly or downwardly within the support frame 42 as described in the following paragraphs first second third and fourth cover panels 44 a 44 b 44 c and 44 d extend between and are coupled to the first and second side frame members 42 b and 42 c a first upper mounting bracket 46 a is coupled to respective upper ends of first side frame member 42 b and third side frame member 58 a similarly a second upper mounting bracket 46 b is connected to respective upper ends of second side frame member 42 c and fourth side frame member 50 b the first and second upper mounting brackets 46 a 46 b are further coupled to the upper frame member 42 a of the frame support 42 and facilitate attaching the support drive mechanism 40 to an upper portion of the.