I got into playing a bit with WPF. I had to look at some reference samples that were created by some of my colleagues and I found that I had an issue opening any xaml file in the visual studio .net 2008 designer. The problem was the VisualStateManager.VisualStateGroups that could not be resolved. Appareantly this is some that has been introduced in the WPFToolkit which is used by our development team.

After some Googling for the issue I discovered a Hotfix released by Microsoft that should resolve my issues. The thing about this hotfix was that you also neede to install another hotfix because the fix might break something else. You gotta love the irony in that!

Anyways the hotfixes I’m talking about can be found here:

• KB958017 – Rollup Hotfix for several issues in WPF designer Visual Studio 2008
• KB963035 – VS2008 SP1 sometimes hangs irretrievably after WPF Designer

After installing both hotfixes the problem was gone I can now open the xaml files that use VisualStateManager.

More information about the VisualStateManager itself can be found here: http://windowsclient.net/wpf/wpf35/wpf-35sp1-toolkit-visual-state-manager-overview.aspx