activeRoot.add(panel1);
activeRoot.add(panel2);
final FakeLayout layout1 = new FakeLayout(true);
final FakeLayout layout2 = new FakeLayout(true);
panel1.markAsNeedingLayout(layout1);
panel2.markAsNeedingLayout(layout2);
loop.doAllLayouts(activeRoot);
assertEquals(panel1, layout1.lastPanelExpanded);
assertEquals(panel2, layout2.lastPanelExpanded);