src/vs/workbench/browser/actions/navigationActions.ts/BaseNavigationAction/toOppositeDirection
class BaseNavigationAction:	private toOppositeDirection(direction: GroupDirection): GroupDirection {
		switch (direction) {
			case GroupDirection.UP: return GroupDirection.DOWN;
			case GroupDirection.RIGHT: return GroupDirection.LEFT;
			case GroupDirection.LEFT: return GroupDirection.RIGHT;
			case GroupDirection.DOWN: return GroupDirection.UP;
		}
	}