Shouldn't you be asking this question to Sun ?

From what I could make out, the OP was referring to his own
*implementation* of the java.awt.LayoutManager2 interface (forgetting
the lower case "m" for a moment).

And by the way :

JLayoutPane is one of the places where you would normally recommend
going in for a null LayoutManager because the LayoutManager or
LayoutManager2 interfaces are in my opinion quite inadequate in
its ability to define a 3 dimensional layout with overlapped components.
(Even JDesktopPane the only descendant of JLayeredPane in the library
does us a null LayoutManager)

BK

Hi,
Trying to be more pedantic now about the upper/lowercase. And being more
precise about the problem. No i didn't subclass JLayoutPane, not even
JLayeredPane.
What i'm trying to accomplish:
---------------------------

---------------------------
I need a few JPanels, (2-4) in upper 80% of view and a few draggable
JButtons in lower 20%. Now i tried this with JLayeredPane and GridLayout
where JPanels were in their own 80% and JButtons were in theirs 20 %.
This also didn't work, the layout was ok, but the layers didn't work. So
i did it with null layout and absolute values and it worked ok. I tried
to do my own LayoutManager which does the same as GridLayout. Idea was
to make simple LayoutManager that AFAIK doesn't kill the setLayer but to
no avail. (I implemented the Java.awt.LayoutManager2)
I'll copy the addLayoutComponent which is called after setLayer:

  public void addLayoutComponent(Component comp, Object parameters)
//if Object is layoutObject
  { //add to vector, with parameters
    if (parameters != null)
    {
      layoutObject my_params = (layoutObject)parameters;
      int inner_container = my_params.getInnerContainer(); //to which
split i belong to
      int orientation = my_params.getOrientation(); //my place in vector
      LayoutVectorObject my_object;
      my_object = new LayoutVectorObject(my_params, comp);
      Vector my_vector = (Vector)vector_collection.get(inner_container);
      if (orientation > 0)
      {
        my_vector.add(orientation,my_object);
      }
      else
      {
        my_vector.add(my_object);
      }
    }
  }

After this the layoutContainer(Container parent) is called, it counts
and sets component to their places. No hassle there. The thing is as you
suspected this addLayoutComponent is called with null values, that's why
i use "if (parameters != null)" to handle them. Should it be handled
differently?

--quote--
So when you call setLayer, it might remove the component from itself and
add it again at a different index, and this will result in a remove and
add calls to the LayoutManager.
--qoute--

If this is the method of setLayer, should i just reorder the components
and "redraw" them myself? I really thought there was a more
sophisticated method for this. Also this might be the origin of the
problem, if setLayer just reorganises the components and redraws them,
and after that the LayoutManager redraws them again, in original order,
the setLayer is of no use. Well i'll check that now and report if that
was the case.
Thanks, Tomi