Display Jenkins pipeline options and script editor in full width.

wide-jenkins.js

// ==UserScript==
// @name         Wide Jenkins
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Display pipeline options in wide screen.
// @author       Victor Toulouse
// @match        http://jenkins-ci.org
// @grant        none
// ==/UserScript==

/**
 * Wait for the script editor to appear.
 */
function check(changes, observer) {
    if(document.querySelector('tr.dropdownList-container:nth-child(215) > td:nth-child(1)')) {
        observer.disconnect();
        document.querySelector('tr.dropdownList-container:nth-child(215) > td:nth-child(1)').style.display = 'none';
        document.querySelector('tr.dropdownList-container:nth-child(215) > td:nth-child(2)').colSpan = '3';
    }
}

(function() {
    'use strict';

    document.querySelector('.container').style.width = '100%';
    document.querySelector('.container').style.padding = '0';
    document.querySelector('.col-md-offset-2').style.width = '100%';
    document.querySelector('.col-md-offset-2').style.margin = '0';

    (new MutationObserver(check)).observe(document, {childList: true, subtree: true});

})();

How I have to use that script?

@unrue you need to install a browser extension like Tampermonkey or Greasemonkey then add the script to it.
But you should use the improved version by @a2intl : https://gist.github.com/a2intl/293a76ae3323ec21d7cdceb6f7cd63af