Microsoft appears to have moved their web developer documentation from MSDN to MDN, making searches from Fiddler's toolbar return useless results.
Please consider making the Search Cue text and Search URL configurable via a preference and set the defaults to "Search MDN" with a URL of https://developer.mozilla.org/en-US/search?q=$SEARCHTERMHERE&topic=apps&topic=html&topic=css&topic=js&topic=api&topic=canvas&topic=svg&topic=webgl&topic=mobile&topic=webdev&topic=http&topic=webext&topic=standards