拖动条显示多了

Start by reproducing the issue with the vertical Split example in the report, using two child divs and the stated 300px height. Trace the Split component's split-bar rendering entry point and determine why two bars appear; done means one functional bar is rendered for the two panes and the requested icon customization behavior is clarified or supported.

我实际给了2个子元素，给我1个split-bar就可以了，但是给了2个，下面的那个bar不能控制，很难看。
另外，有办法自定义bar的icon吗？

<Split mode={'vertical'} style={{height: '300px', overflow: 'hidden'}}>
  <div style={{ height: '50%', overflow: 'auto' }}>
    By dragging 'draggable' surface you can change size of the first pane. The first pane keeps then its size while the second pane is resized by browser window. By default it is the left pane for 'vertical' SplitPane and the top pane for 'horizontal' SplitPane. If you want to keep size of the second pane and let the first pane to shrink or grow by browser window dimensions, set SplitPane prop primary to second. In case of 'horizontal' SplitPane the height of bottom pane remains the same.
  </div>
  <div style={{ height: '50%', overflow: 'auto' }}>
    By dragging 'draggable' surface you can change size of the first pane. The first pane keeps then its size while the second pane is resized by browser window. By default it is the left pane for 'vertical' SplitPane and the top pane for 'horizontal' SplitPane. If you want to keep size of the second pane and let the first pane to shrink or grow by browser window dimensions, set SplitPane prop primary to second. In case of 'horizontal' SplitPane the height of bottom pane remains the same.
  </div>
</Split>