Extending a component which already extends a spark list ItemRenderer

Question

Hello everyone,
I have the following situation: Im displaying lists of very similar data objects (they extend the same parent) so in order to avoid a lot of changes to many itemrenderers (if i need to change something in the common properties) when displaying this data, i defined a spark list ItemRenderer (in MXML) which displays the common properties (file called BaseRenderer.mxml):
<s:ItemRenderer>
     //in the script section i override the set data property
     //some MXML labels, checkboxes, etc
</s:ItemRenderer>
Then i created a specific itemrenderer which extended it (file SpecificRenderer.mxml):
<model:BaseRenderer>
     //again i override the set data property
     //some ADITIONAL MXML labels, checkboxes, etc
</model:BaseRenderer>
When i run the app, and when the specific renderer is used, it works (no errors are thrown) , but it only shows the content of specific renderer, nothing from base renderer is visible. Is this the right way to do this, or do i have to override some additional stuff in my specific renderers?
Thank you.
One more thing, i just noticed, if i remove all MXML tags from specific renderer, the content from base renderer becomes visible, seems as if specific content overrides base content. Is there a way to add mxml tags into the specificrenderer?

Answer 1

Yes i suspected them to be merged, and you gave me a great idea. As you say this behavior is true across all mxml defined components, not just itemrenderers. I want to avoid actionscript renderers because i dont (and wont) have any performance issues anyway and i like flexibility in design view, so instead i found another solution which i slightly modified. Some spark components inherit property mxmlContent, which you can override. This is what i came up with in the end: I added the property override into specific renderer and everything is shown as expected (because base elements are merged with the ones from extended component).
override public function set mxmlContent(value:Array):void {
                                        var adding:Boolean = true;
                                        var index:int = 0;
                                        while (adding) {
    var element:IVisualElement = null;
    try {          element = super.getElementAt(index); } catch(e:Error) {          }
    if ( element != null )  {
       value.push(element);
       index += 1;
    else
      adding = false;
                                        value.reverse();
                                        super.mxmlContent = value;