...
He also wants to transpose the entire piece up a bit, so he double-taps to bring up the menu. He chooses 'edit'->'select all', and then drags a note up to transpose the whole piece.
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Analysis
Learnability
This user interface was designed to be as intuitive as possible, and gives brief explanations of features as the user encounters them. Overall it should be pretty learnable.
Efficiency
The interface is designed with efficiency in mind -- a user should be able to do things quickly and easily. Some of this is necessitated by the smartphone platform, as the limited screen real estate forces us to put less-commonly used tools in a hidden menu.
Safety
Any action short of deleting a note or a file should be fully reversible with a similar action. For instance, moving a note to the wrong pitch can be undone by simply moving the note again.