question: public boolean onGenericMotionEvent ( MotionEvent ev ) { if ( ( ev . getSource ( ) & InputDevice . SOURCE_CLASS_POINTER ) == InputDevice . SOURCE_CLASS_POINTER ) { int action = ev . getAction ( ) ; switch ( action & MotionEvent . ACTION_MASK ) { case MotionEvent . ACTION_SCROLL : float vScroll = ev . getAxisValue ( MotionEvent . AXIS_VSCROLL ) ; if ( vScroll > 0 ) { if ( mDeckView . ensureFocusedTask ( ) ) { mDeckView . focusNextTask ( true , false ) ; } } else { if ( mDeckView . ensureFocusedTask ( ) ) { mDeckView . focusNextTask ( false , false ) ; } } return true ; } } return false ; }
target:  Handles generic motion events