Type Number Event userInput Revision Release 2025.3721 Keywords userInput, startPosition 
The position where the cursor was when the event took place.
This property is only available during the "editing" phase of userInput events.
local function textListener( event )
    if ( event.phase == "editing" ) then
        print( event.startPosition )
    end
end
defaultField = native.newTextField( 150, 150, 180, 30 )
defaultField:addEventListener( "userInput", textListener )