Shifting Glass Panes

aThe Shifting Glass Panes are found in Checkpoints 2 and 4. Unlike their slower counterpart, the Sliding glass panes, they move at regular intervals, and quicker too. They are a better target for Balls because their faster movement exploits the dragging effect, spreading the force of the balls out so the whole pane is broken. In Checkpoint 4, the glass is double-thickness.