Alternative for multipoint gestures (single-point-alternative)
Verify that all interactions which rely on multiple fingers (e.g., pinch or zoom) have an alternative method (such as a button) provided to achieve the same functionality with a single pointer.
Path gesture to undo with no single-pointer alternative:
This interface uses a "Z" gesture to undo the last action. However, it does not provide a simple tap or click method to perform the same undo function:
Draw a "Z" to undo