How can I control all user events fired in a browser?

I would like to track all user events triggered in a web browser. Any standard browser will do.

To be clear, I know that you can attach event handlers to see when "regular" events are fired, but how can I reliably determine if an inline object or jQuery script is firing a custom event?

I could reorganize the source code of the browser to intercept the event loop, but it looks pretty extreme.