Best Practice 2.14 – Avoid accidental screen touches or allow user to undo actions (Baseline level)

Functions should be initiated by the up-event (i.e. release the finger from the screen) instead of down-event (e.g. finger touched the screen). It is also considered as accessible if either one of the following mechanisms is provided:

To abort the function before completion; or
To undo the function after completion.

There is exemption when the down-event is essential such as in the piano keyboard emulation program.

Before Rectification	After Rectification To switch on the light

The lighting will turn on after user touches the “switch on” button on the mobile app panel. Under this design, function will execute immediately when the finger touch the screen, even if user accidentally touches the screen.	The lighting will turn on after user touches and releases his finger from the “switch on” button of the mobile app panel.
	To cancel the action
	The application should allow user to cancel the action by dragging the finger out of the button area and lift the finger.