I suggest the insertion in the code to allow as well the press of 'Enter' button to go to Previous Page.
The key code for 'Enter' is 28.
Also, can there be the insertion of a condition argument check, to check if the screen shows a menu (i.e. not in page reading mode) and if it is in menu mode, the Next Page command is not executed. This would solve some minor problem when you try to insert a command from the menu.