stack = new StackLayoutPanel(Style.Unit.PX);
stack.addStyleName("section-stack");
serversSection = new ServersSection();
stack.add(serversSection.asWidget(), new StackSectionHeader("Server Configurations"), HEADER_SIZE);
instanceSection = new InstancesSection();
stack.add(instanceSection.asWidget(), new StackSectionHeader("Server Instances"), HEADER_SIZE);
hostConfigSection = new HostConfigSection();
stack.add(hostConfigSection.asWidget(), new StackSectionHeader("Host Settings"), HEADER_SIZE);
// -----------------------------
layout.addNorth(selectorWidget, SELECTOR_HEIGHT);
layout.add(stack);