Removes the "position: fixed" attribute on the new header bar on Tumblr.

tumblr_unfixNewHeader.user.js

// ==UserScript==
// @name         Un-fix new Tumblr header
// @author       sin_sin
// @namespace    https://gist.github.com/sinsinpub
// @version      0.1b
// @description  Removes the "position: fixed" attribute on the new header bar on Tumblr.
// @copyright    2014, sin_sin
// @match        http://www.tumblr.com/dashboard
// @include      *://www.tumblr.com/dashboard*
// @grant        none
// ==/UserScript==

(function() {
    var header = document.querySelectorAll(".l-header-container");
    if (!!header && header.length > 0) {
        header[0].style.position = "absolute";
    }
})();