On the design time error please examine this forum thread
. It is related to an older version of the RadControls for ASP.NET AJAX, yet if you have had it installed while working with this project this may still be applicable.
This design time error is caused by having two instances of the Telerik.Web.UI assembly having different versions, loaded in the same Visual Studio AppDomain.
Besides the problem, described in the article, this could happen as a result of a reference update, e.g: a page with RadControls was loaded in design mode, the reference was updated and the page got reloaded again. This is a one-time only problem and its fix involves a Visual Studio restart.
Another possible reason for that is that the solution contains multiple projects, each referencing a different RadControls for ASP.NET AJAX assembly. Thus, loading a page with a RadControl from ProjectA in design mode and loading a page with a RadControl from ProjectB could result in the TypeCastException.
In that case I would suggest that you either update both the projects to use the same RadControls assembly, or split the projects to different solutions. Please, restart Visual Studio after any of the approaches.
On the matter with the GridView - please make sure if the GridView renders at all in the page. You can do so by examining the rendered HTML with a tool like firebug or the IE Dev Toolbar. It is possible that some of the containers have specific height set or have their height set as 100% and are, therefore invisible because of some inherited size properties. You can confirm this via the UpdatePanelHeight property of the AjaxUpdatedControl inner tag. Try setting it to 100% or to some hard value in pixels. If this starts showing the GridView please examine the DOM tree for missing sizes and set them accordingly.
What I meant for the Demos was that you can start off with this runnable page and replace the RadGrid with your GridView (of course, the code-behind needs to be altered a bit to accommodate the different events from the GridView that will add the client-side handler, which opens the RadWindow). Once this project runs as expected the same settings should be applicable for your original project as well.
All the best,
the Telerik team
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