Incorrectly rendered Telerik controls inside a UserControl

[Tomasz M.Lipiński]

Hi,
I've encountered a ridiculous problem - occuring when using IE only (IE 8; I've not tested other IE versions); NOT occuring when using FireFox, Opera, Chrome or Safari.
My page consists of two UserControls:

<asp:Panel ID="pnlMain" runat="server">
  <uc1:ProcessGridViewEmb ID="embGrid" runat="server" />
  <uc1t:ProcessTreeViewEmb ID="embTree" runat="server" />
</asp:Panel>

There are some scripts loaded above this markup (RadScriptManager; Core.js and jQuery.js of yours plus some my scripts).
embGrid consists of two tabs (RadMultiPage + RadTabStrip); the first of them contains a RadToolBar + RadGrid, the second - a RadToollBar + some minor controls.
embTree consists of a RadToolBar and a RadTreeview.

Let's have a look at embTree (precisely: the RadTreeview inside it). It should look like on tree_ok.jpg (see attached print-screens). But when placed as above it is displayed completely incorrectly: tree_bad.jpg. But - attention - when I change the order of the controls (embTree first, then embGrid), embTree starts to be displayed correctly. Is looks (in the first case) like not all CSS needed for the control has been loaded. I've attached print-screens with the actual markup (I've used the tools from IE 8).

As I've mentioned above all other browser render these control correctly in all the cases.
I'm using Q1 2010 version of Telerik controls.
Is it possible to explain this mystery?

Regards
Tomasz

[Veli]

Hi Tomasz,

Do you have any custom CSS on your page that may be interfering with the rendering of the RadControls? If so, try disabling these to see if this is the cause. Also, can you send us some test page or a live URL we  can examine? This will help use better identify the problem.

Veli
the Telerik team

[Tomasz M.Lipiński]

Hi,
I've continued investigations according to your suggestions:
- there are no local styles embedded in aspxes or ascxes
- all CSS files are imported using the ASP.NET mechanism of "App_Themes"
- there are two CSS files there, with my own CSS rules
And further:
- removed both of them: works well
- restored any one of them: works well
- restored two of them but with empty content: works bad
- removed both and replaced by any empty files (xx.css and yy.css): works bad
- both original files packed in a single CSS file: works well
Interesting, isn't it?
And finally I've got a sudden idea :-) and added an instance of RadStyleSheetManager to the top aspx ("runat" and "id", nothing more): it works WELL.

So, OK, let's assume that this is the solution. Otherwise - I'll be back :-)

Regards
Tomasz