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Third Party ASP.NET Controls and Visual Studio 2008

We've had a few cases recently where customers are using third-party ASP.NET server controls (either written by a third-party company or by the customer) and finding that the controls are not rendering correctly in the Visual Studio 2008 design surface. Most recently, we had an issue where a popular third-party control company's custom property editor was not working correctly in Visual Studio 2008.

In all of these cases, we've investigated the issue and found the problem to be that as the third-party was developing their controls in Visual Studio 2005, they relied on our implementation in the Visual Studio design surface. What they did not anticipate was that our implementation would change with Visual Studio 2008.

The HTML design surface in Visual Studio 2008 is completely new. In order to get a much better representation of page rendering and to add new features, we incorporated the Expression Web design surface into Visual Studio 2008. (That decision also gives you the great new CSS features in Visual Studio 2008.) In almost all cases, controls that were developed against Visual Studio 2005 will work without any problems, but there are cases where the change in the designer causes undesirable behavior for server controls built against Visual Studio 2005. For example, one company found that the hierarchy of the control tree in the Visual Studio 2008 designer differed slightly from Visual Studio 2005. This change caused their control's code to incorrectly parse the page.

It is highly unlikely that you will encounter a problem with any controls in the Visual Studio 2008 designer. If you do, it's very likely that a change will be required in the control itself in order to take into account any implementation changes in the new designer.

Jim