AS3: global var of type SimpleButton changes to DisplayObject for unknown reason, won't let me access .upState.textColor!

This is a problem that's best explained in code.

I don't see how active_button.upState, which I know is a TextField (see trace statements), mysteriously turns into a DisplayObject when I try to access the textColor property.

I've included the error messages below for reference.

Also, why is it that when I have an object that I know is a SimpleButton (again, see traces) I need to cast it to SimpleButton in order to store it in a var? That doesn't make any sense to me.

All help is much appreciated. Thanks.

public class Menu extends MovieClip
{
    private var active_button:SimpleButton;

    public function Menu() 
    {
        // menu_list is a collection of SimpleButtons, I make the first one the 'active_button' and give each a MOUSE_DOWN event listener.
        trace( menu_list.getChildAt( 0 )); // writes [object SimpleButton]
        active_button = SimpleButton( menu_list.getChildAt( 0 )); // Cast is required here. Otherwise throws Error 1118. Strange. Why is that?

        for( var i:Number = 0; i < menu_list.numChildren; i++ )
        {
            menu_list.getChildAt( i ).addEventListener( MouseEvent.MOUSE_DOWN, menuClick );
        }
    }

    private function menuClick( e:Event ) : void
    {
        trace( e.target ); // writes [object SimpleButton]
        active_button = SimpleButton( e.target ); // Cast is required here. Otherwise throws Error 1118. Still Strange.
        trace( active_button ); // writes [object SimpleButton]. Normal.
        trace( active_button.upState ); // writes [object TextField]. Normal.
        active_button.upState.textColor = 0xAAAAAA; // Throws Error 1119. WTF?! textColor is a perfectly valid property of active_button.upState. Why is it suddenly type DisplayObject?
    }
}

ERRORS:

1118: Implicit coercion of a value with static type flash.display:DisplayOb开发者_StackOverflow社区ject to a possibly unrelated type flash.display:SimpleButton.

1119: Access of possibly undefined property textColor through a reference with static type flash.display:DisplayObject

EDIT: I've condensed my question a little bit and posted as AS3: Why does datatype automatically change from TextField to DisplayObject on its own?

Anything that is pulled from the displaylist is classed as the lowest possible dinominator (eg. displayObject), as although SimpleButton is a displayObject, not all displayObjects will be SimpleButtons. This is probably the reason for your second problem too, just slightly different in execution. is there a direct reference in SimpleButton that states upState is a TextField?

try switching off Strict Mode of compilation and see if it helps. see Type Checking Livedocs for more information