Bookmarklet to selects all of the last opened gmail message.

selectAllGmail.js

/*
 * Selects all of the last opened gmail message.
 */
(function() {

  function setSelection(el) {
    var range = document.createRange();
    var fst = el.firstChild, lst = el.lastChild;
    if (fst && lst) {
      range.setStartBefore(fst);
      range.setEndAfter(lst);
    } else {
      range.setStartBefore(el);
      range.setEndAfter(el);
    }
    var sel = window.getSelection();
    sel.removeAllRanges();
    sel.addRange(range);
  }

  function getNthNode(par,n) {
    if (!par) return null;
    if (par.childNodes.length <= n) return null;
    return par.childNodes[n];
  }

  function main() {
    var msgDiv = document.querySelector('div[style="display:"]');
    if (!msgDiv) return;
    var bodyDiv = getNthNode(msgDiv, 2); // gross
    if (!bodyDiv) return;
    var el = getNthNode(bodyDiv, 5); // gross!!
    if (!el) return;
    setSelection(el);
  }

  main();

})();