Running the demo on my end does not lead to JS errors or alerts. Further, the control seems to be working as expected. I recorded a screencast for you to examine—http://screencast.com/t/CMn7jGS6
I suggest checking if you are able to reproduce the same by using different machine. This might be related to a browser plugin or configuration.
Without reproducing this locally, I can only make guesses what the exact reason might be.
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