A friend worked with a high end image manipulation program that had "pie" menus. You held the menu button down on your tablet, and after a pause a circular menu

A friend worked with a high end image manipulation program that had "pie" menus. You held the menu button down on your tablet, and after a pause a circular menu popped up at the mouse position. You dragged in the direction of your choice. If there were submenus for that choice, another circle popped up and so on. Because of fitts' law, this was far more efficient than standard popup menus: the 'target' for any choice was larger and therefore much easier to hit. The gestural part was this: If you held the menu button down and immediately started to move the mouse, it would select the choice without bothering to display the pie. Advanced users quickly learned the sequence of zigs and zags required for their most common menu operations and preferred using the pie menus to keyboard shortcuts or standard menus in the window panes. As the OP points out, this system provided discoverability as well as consistency. The same gesture always produced the same result.