ADG initilizes private vars for unknown reason

[mark goldin]

I have an ADG where I am using a local connection to refresh gird's data
and select previously selected item.
The pseudo code might loook like this:

private var _selectedIndex:int = 0;
private var _navigateToPrevSelection:Boolean = false;

private function get SelectedIndex():int
{
return _selectedIndex;
}
private function set SelectedIndex(value:int):void
{
_selectedIndex = value;
}
private function get NavigateToPrevSelection():Boolean
{
return _navigateToPrevSelection;
}
private function set NavigateToPrevSelection(value:Boolean):void
{
_navigateToPrevSelection = value;
}
// This function is called when the server has returned a coomand that
grid's data must be refreshed.
public function localConnectionHandler():void
{
     SelectedIndex = grid.seledctedIndex;
     // an event "ABC" is fired to generate new data for the grid.
     // set dataProvider is called since grid's data is bound to the ABC's
execution result
    // At this point SelectedIndex has the correct value;
}
override public function set dataProvider(value:Object):void
{
// When dataProvider is set after ABC was executed the SelectedIndex is set
to _selectedIndex's initial value which is zero.
        if (value)
        ....
}

Can someone please explain why private variables get initialized?

Thanks