A connecting structure detachably connects the upright post of a floor support to the upright frame supporting a panel lift device. The upright post has a pair of upright panels diverging forward to form a V shaped flange that has its lower portion open in front and a rounded knob mounted at the bottom of the post and spaced forward from the forward diverging V shaped flange. The post also has a pair of upright panels converging forward with upper portions of the panels tapering toward one another to form a pointed V shaped upper end. The frame has a forward diverging V shaped flange with an upper portion having dual pair of forward converging flanges in spaced relation to one another to form a forward converging V shaped slot. The upright frame has lower edges formed of a pair of upright rearward converging flanges to be detachably received in the rearward converging space between the rounded knob and V shaped flange of the post with the pointed upper end of the post detachably received in the V shaped slot of the frame for detachably mounting the post of the floor support to the upright frame of the panel lift device.