User scripting new GMail messages

With the recent change in how GMail works, lots of prior user scripts improving the service, like a small hack that removes <font size="+1"> tags from mails broke, in the wake of the DHTML improvements (which make the site more difficult to augment via user scripting).

The GMail developers, generously, were not very far behind to release a smallish Greasemonkey API, somewhat alleviating the problem -- but it still is less than trivial to target mail bodies with your user scripts.

I took a stab at it the other night, to figure out what would go into it, and managed to come up with a new font manhandler (it targets a rather local nuisance on the Greasemonkey mailing lists). As I have been trying out MailPlane for a while for reading my mail I decided to see if I could make the script run both in Firefox on Greasemonkey and Safari/WebKit/MailPlane on the GreaseKit user script manager. That turned out quite doable. The script, in its entirety:

// ==UserScript==
// @name           Gmail - deBill:ifier
// @namespace      http://code.google.com/p/ecmanaut/
// @description    Manhandles all font size tags to stop all the yellin'
// @include        https://mail.google.com/*
// @include        http://mail.google.com/*
// ==/UserScript==

window.addEventListener("load", loader, false);

function loader() {
  var api = typeof unsafeWindow != "undefined" && unsafeWindow.gmonkey ||
    (frames.js ? frames.js.gmonkey : null);
  if (api) api.load("1.0", init);
}

function init(gmail) {
  function viewChanged() {
    var view = gmail.getActiveViewType();
    if ("cv" == view) {
      var div = gmail.getActiveViewElement();
      div.addEventListener("DOMNodeInserted", deBill, false);
    }
  }
  gmail.registerViewChangeCallback(viewChanged);
}

function deBill(event) {
  var font = event.target.getElementsByTagName("font");
  for (var i = 0; i < font.length; i++)
    font[i].removeAttribute("size");
}

Feel very free to base your own hacks on the recipe. I recommend starting out with an action function that does something basic like setting event.target.outline = "1px solid red", to see where it does what it does -- since the callback runs for every conversation view change, including updates to the ad pane on the right, not only when expanding mails you read.