Making a Dock app and want to know what is possible.

The order of them is just due to the installation order at the moment (although I guess it might make sense to have a 'sortorder' field in there). Nothing stops you from changing the order if items in the WIDGETS object though:

function moveToRight(n) {
  var w = WIDGETS[n];
  delete WIDGETS[n];
  WIDGETS[n] = w;
}