[flexcoders] getting refs to items in Group.mxmlContent?

[Mic]

(OK to ask Gumbo questions?)When an .fxg file is loaded into 
FxApplication and added to a Group, and that Group is then added to 
FxApplication, array mxmlContent[0] contains the .fxg Graphic object, 
whose child Groups can be accessed directly by name:

displayGroup.mxmlContent[0].myGroup1

However I cannot access mxmlContent[0] with getChildAt() etc, nor can 
I work out how to extract out references to mxmlContent[0] into 
another array etc so a list can be displayed where a Group object 
might be selected. Can find no info on mxmlContent :-(

code:
  testFXG.fxg contains group id="myGroup1", group id="myGroup2" etc

  private var displayGroup:Group;  
  displayGroup = new Group();
  var source: testFXG= new testFXG();
  displayGroup.addItem(source);
  addItem(displayGroup);

breakpoint shows:

displayGroup
  [inherited]
  mxmlContent
    [0]
      myGroup1
      myGroup2
      etc

code:
  private var testGroup:Group;
  testGroup = displayGroup.mxmlContent[0].myGroup1;

 - this is a good reference and can be used to change myGroup1.x, 
myGroup1.y etc. However as stated above I cannot get a reference to 
e.g. the 3rd child etc. As always, TIA,

Mic.