title: How to hijack key combos in javascript?
body: <p>In Gmail, for example, when one presses <kbd>Ctrl</kbd> + <kbd>B</kbd>, instead of it getting passed to the browser (which would normally bring up some sort of bookmark manager), it hijacks it for formatting purposes, i.e. turn on bold formatting for the message ur in the middle of comoposing.  Same for <kbd>Ctrl</kbd>+<kbd>i</kbd>, <kbd>Ctrl</kbd>+<kbd>u</kbd>.  </p>
  
  <p>How is this done?</p>