This took me 2 hours to find out how to disable textfield on AS3, its not the perfect solution but it seems to be the only solution.

private var txtField:Textfield;
…
this.txtField = this.getChildByName(”txtField”);
this.txtField.mouseEnabled = false;
this.txtField.tabEnabled = false;

and to turn it enable again:
this.txtField.mouseEnabled = true;
this.txtField.tabEnabled = true;

While this sound cheap coz you have to disable the mouse and the tab of that component and not the component itself, it seems to be the only solution. Thanks Adobe!!!!!!!!