Combo "onDropdown" event?

I am trying a AW Combo. How can I trigger a "onDropdown" event? I have tried combo.onControlClicked, but it seems only triggered on the combo's textbox clicked. When I click the combo's "dorpdown" button, I like to show up an alert. Could you give me an example?

Thanks

Try onControlMouseDown or onControlMouseUp. You can also overwrite showPopup() method.

I still need the build-in showPopup() method. How can I add some function on it instead of overwriting it?

Thanks,

Save the original showPopup method and call it from your code -

combo.showPopup1 = combo.showPopup;
combo.showPopup = function(){
    alert(123);
    this.showPopup1();
}