Replacement for "one", which will run the bound event-handler once for each element that triggers the event, vs. current "one" that will run only once for the first element that triggers the event. jQuery >= 1.7 required (or 1.4.3 with on/off shim).
Example:
$(document).onFirst('focus', 'textarea.mywidget', function(){
// hook up "mywidget"
});
Note: the only way to unbind this is to call "off" with the same event name and selector, without passing the handler.