public void insertUpdate(DocumentEvent changes,Shape a,ViewFactory f){
  updateChildren(changes,a);
  Rectangle alloc=((a != null) && isAllocationValid()) ? getInsideAllocation(a) : null;
  int pos=changes.getOffset();
  View v=getViewAtPosition(pos,alloc);
  if (v != null)   v.insertUpdate(changes,alloc,f);
}

public void insertUpdate ( DocumentEvent changes , Shape a , ViewFactory f ) { updateChildren ( changes , a ) ; Rectangle alloc = ( ( a != null ) && isAllocationValid ( ) ) ? getInsideAllocation ( a ) : null ; int pos = changes . getOffset ( ) ; View v = getViewAtPosition ( pos , alloc ) ; if ( v != null ) v . insertUpdate ( changes , alloc , f ) ; }
gives notification that something was inserted into the document in a location that this view is responsible for . this is implemented to simply update the children .
