Combination flex and torsion springs for use with light weight covers for containers having self-closing gates, the springs operatively connecting the gates to surrounding cover portions. A tri-fold seam including a frangible seam works cooperatively with the flex-torsion springs to implement three modes of operation of the gates. In a first mode, the gate returns to a reclosed orientation after removal of downward pressure. Further pressure on the gate engages a toggle operation that locks the gate open. In a third mode, if the gate is pushed even further downward, the toggle mechanism is defeated and the combination flex-torsion spring is forced past its elastic limit and the gate remains in a permanently open orientation. The flex-torsion springs in accordance with the invention may be fabricated from aluminum sheet stock or spring wire.