cord 86 beneath the first horizontal pivot pulley 78 is pulled downward the first outer pivot arms 94 are pivoted toward the first horizontal pivot pulley 78 and the second inner pivot arms 96 are pivoted toward the fourth horizontal pivot pulley 84 thus rotating the first and second spool members 38 40 in a first direction when the portion of the horizontal pivot cord 86 beneath the first horizontal pivot pulley 78 is pulled upward the first outer pivot arms 90 are pivoted toward the second horizontal pivot pulley 80 and the second outer pivot arms 94 are pivoted toward the third horizontal pivot pulley 82 thus rotating the first and second spool members 38 40 in a second direction when the frame 56 is pivoted to a vertical position so that the panels 16 are oriented vertically as shown in fig8 then the panels 16 may be rotated into the position shown in fig1 by pulling the horizontal pivot cord 86 and causing the first and second spool members 38 40 to rotate as described above a first tension cord 88 is strung between first inner pivot arms 92 which are connected to the first spool members 38 a second tension cord 89 is strung between second outer pivot arms 94 which are connected to the second spool members 40 the first and second tension cords 88 89.