sectionStack.setSize("300px", "100%");
// LayerTree layout:
SectionStackSection section2 = new SectionStackSection("Layer tree with legend");
section2.setExpanded(true);
layerTree = new LayerTreeWithLegend(map);
section2.addItem(layerTree);
sectionStack.addSection(section2);
// Putting the right side layouts together: