1) With version 3 I was including object names as part of the trigger. The idea was that, for new users, typing 'Window' would produce a list of members for the Window object. However, because it's part of the trigger, it means that a lot of unwanted items might appear in the completions list. In version 4 the object names are just completion-descriptions.
2) In version 3,typing 'alert' would prepend 'window' if there wasn't already a reference to this object typed. I've removed this feature. However, I've kept it for Math, static-methods. That is, I can type 'abs' and it will create 'Math.abs()'.
[I was fond of this prepending but: it's unfamiliar behaviour; a lot of programmers are happy to assume 'Window', or already create a variable that references the Window object.]
3) I've removed the underscore from the trigger for css-properties. Again, it was unfamiliar, and was unnecessary - particularly as the css properties are listed last in the completions file.
4) I've added $0 to the end of completions that include parameters. I think it's clearer and I prefer to tab out of the brackets.