Hi Piet Koole,
Unfortunately, this is exactly the case. Officially, VS2008 doesn't support design-time for Silverlight projects and because of this we do not install our controls.
In VS2010 the problem is solved and controls are automatically installed (of course, if you do not perform custom installation and exclude them). Also, each control has its own icon.
If you have another questions do not hesitate to contact us.
the Telerik team
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