ActionScript 3.0 :: Base Class Does Not See Stage Instances

I'm writing a series of Search windows for an application. I create the FLA files on the stage, each has 3 simple buttons: next_btn, prev_btn, and close_btn. Those all have event listeners which call findNext(), findPrev() and closeWin() respectively. Each search window looks for different things, some with a text box and some with a combo, etc.
 
So I have a base class com.search that extends Sprite and adds the eventListeners at startup (actually, on addedToStage). Like this:
 
function isAddedToStage(evt:Event){
next_btn.addEventListener("click",findNext);   prev_btn.addEventListener("click",findPrev);   close_btn.addEventListener("click",closeWin);}

[Code]....
 
If I add the event listeners in the derived class rather than the base, it works fine. But that seems to defeat the purpose of inheritance, plus it infers that I won't be able to derive new classes/swfs from those derived classes.
 
how does one reference objects created on the stage from a base class of that document's class?