Accepted characters are ASCII values in the range 32 to 126 inclusive. If a virtual keyboard is required for text entry on this device then it will be displayed over your app. You cannot assume that any part of your app will be visible whilst text entry is in progress, although your code will continue running. 

When the user has finished entering text Completed will return True and Cancelled will let you know if they completed the text entry or cancelled it. 

On keyboard based devices cancelling is done with the escape key whilst completing is done with the enter key. If sucessful you can get the inputted text with Input. 

There is also a version of Start that fires a notification event instead on completion.

Start Method