It seems that there is something not right with the intellisense of VisualStudio. The intellisense demonstrated in the attached picture looks like the one for HTML code. The suggested events and properties are for HTML. Can you please try to delete manually the "bin"
folders from projects and then Clean and Rebuild the solution? You can also try to clean the Visual Studio cache and see if the issue still occurs.
As for the event in Silverlight (and WPF) it is called Click, not onclick.
I hope this works.
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