I think one of the reasons Jon manages to pull it off so well is how basic it is. He has a 100% custom sidebar (very basic), but other than that he is using native menu controls and standard dialogs. Obviously the editor pane is the big custom component.
That's a good point. I think one of the reasons Sublime works so well is because the interaction is minimal and unobtrusive. You don't realise how simple the controls are - as you said; standard dialogs etc.
