I made a minor modification to your sample in order to resolve the issue. The changes are listed as follow:

• Remove WebTreeView out of the ASP:Panel control.

  Original code (WebForm1.aspx)

  ...
  <asp:Panel ID="Panel1" runat="server">
      <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
      <ISWebTreeView:WebTreeView ID="WebTreeView1" AllowMultipleSelect="false" runat="server"
          Height="500px" Width="400px">
      </ISWebTreeView:WebTreeView>
  </asp:Panel>
  ...

  Modified code (WebForm1.aspx)

  ...
  <asp:Panel ID="Panel1" runat="server">
      <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
  </asp:Panel>
  <ISWebTreeView:WebTreeView ID="WebTreeView1" AllowMultipleSelect="false" runat="server"
      Height="500px" Width="400px">
  </ISWebTreeView:WebTreeView>
  ...

• Enable RequiresUIRefresh property and add RefreshModifiedControls() method.

  Original code (WebForm1.aspx.cs)

  ...
  WebTreeView1.ExpandAll();
  
  uiService.ClientAction.UpdateViewState();
  uiService.ClientAction.RenderControl(Panel1);
  ...

  Modified code (WebForm1.aspx.cs)

  ...
  WebTreeView1.ExpandAll();
  
  uiService.ClientAction.UpdateViewState();
  WebTreeView1.RequiresUIRefresh = true;
  uiService.ClientAction.RefreshModifiedControls();
  uiService.ClientAction.RenderControl(Panel1);
  ...

This should helps. Please have the changes tested on your end and let us know whether it helps or not.

Hi Yudi:

    I want to refresh the panel because in the demo below it has anther problem.I use webflypostmanager to render webtreeview directly. but it works very slowly.sometimes the browser seems die.This is a big problem,please give me some advise.

Thanks

he peng

Can anybody help me?

Hello,

I make a simple test and it seems the process random that caused the rendering process slowly. I just want to know, what are purpose to use this random logic. Do you have some needed or something? Thank you.

Regards,
Handy

Actually I don't need the random logic.I just want to show different data in refresh. If I don't use random logic,the rendering process is also slow.In my opion, it seems Webpanemanager or usercontrol cause the problem.In a single page, the process of rendering a webtreeview in a webpanemanager will not cause the problem.

Regards

he peng

I was unable to get the demo.rar sent sample run on my local test.
Could you please give us a step-by-step guide or a running simple sample that we can use to observe the problematic behavior?