1<PanelGroup direction="horizontal">
2  <Panel>
3    left
4  </Panel>
5  <PanelResizeHandle />
6  <Panel>
7    <PanelGroup direction="vertical">
8      <Panel>
9        top
10      </Panel>
11      <PanelResizeHandle />
12      <Panel>
13        <PanelGroup direction="horizontal">
14          <Panel>
15            left
16          </Panel>
17          <PanelResizeHandle />
18          <Panel>
19            right
20          </Panel>
21        </PanelGroup>
22      </Panel>
23    </PanelGroup>
24  </Panel>
25  <PanelResizeHandle />
26  <Panel>
27    right
28  </Panel>
29</PanelGroup>