and a fixed mullion 4 when the door 1 is fully entered into the recess 2 a weather seal in the form of a rubber gasket 5 or other elastomeric seal is compressed between the door 1 and a lip 6 which extends completely around the recess 2 two crank shafts 7 and 8 run the height of the door 1 to the foot of each crank shaft 7 and 8 there is fixed a respective crank arm 9 or 10 each of crank arms 9 and 10 is supported upon a respective trolley 12 or 13 to which the respective crank arm 9 or 10 is connected by a pivot pin 14 or 15 each trolley 12 and 13 runs on wheels on a slide track 16 the weight of the door 1 rests on the crank arms 9 and 10 through which in turn the weight rests on the trolleys 12 and 13 and from there through the trolley wheels the weight of the door 1 rests on the slide track 16 the trolleys 12 and 13 are free to slide independently of each other along the slide track 16 when the crank arms 9 and 10 are rotated in the manner as shown in fig2 the two trolleys 12 and 13 start to approach each other by sliding along the slide track 16 since the trolleys 12 and 13 cannot move rearwardly with respect to the slide track 16 and the door panel the door 1 therefore starts to move out of the recess 2 as.