I have a problem with the rendering of certain web controls in design view on the VS2010 webforms editor.
Specifically, controls that are defined in the System.Web.Extensions DLL (such as UpdatePanel and ListView) don't render in design view if they are present in a user control that is nested to at least a level of two. I don't see the problem if I use 'standard' controls, such as Label, Image etc., which are not defined in System.Web.Extensions.
This only seems to affect design mode in Visual Studio. The rendered content when a user control is used on an aspx page is as expected.
To reproduce the problem, I did the following:
Create three user controls: A.ascx, B.ascx and C.ascx.
In A.ascx, add a single UpdatePanel,
In B.ascx, add a single instance of A.ascx,
In C.ascx, add a single instance of B.ascx.
So, the markup for these is:
A.ascx Go to the complete details ...