[flexcoders] Form validation before submitting...

[Laurence MacNeill]

Ok, I figured I could loop through all the children of my form, 
checking their .errorString to make sure it's blank, and if it's not 
blank then assuming there's an error on the form.

So, why won't this code work?  It won't compile -- gives me two 
errors, "Attempted access of inaccessible method numChildren through 
a reference with static type components" and "Access of possibly 
undefined property errorString through a reference with static type 
flash.display:DisplayObject"

Here's the code:
private function formIsValid():Boolean {
         var validForm:Boolean = true;
         for (var i:int = 0; i < this.numChildren(); i++) {
                 if ( (this.getChildAt(i)).errorString != "" ) {
                         validForm = false;
                 }
         }
         return validForm;
}