How to determine the last time a user input was received in Silverlight 3

I have a Silverlight 3 application, and in a method, I want to determin开发者_如何学Goe when the last time that the application received user input was. Is there an easy way to detect this?

I doubt there is framework support for such a value, but you should be able to roll your own easily enough by monitoring key, mouse and other input events and setting a timestamp value accordingly. You could even persist this in isolated storage to carry the value across sessions (provided the user has not disabled isolated storage of course).