twitter-oauth-caution.user.js

// ==UserScript==
// @name           Twitter OAuth Caution
// @namespace      http://github.com/mooz/
// @description    Display caution when application requests a 'write' access
// @include        https://twitter.com/oauth/authorize?*
// @include        https://twitter.com/oauth/authenticate?*
// ==/UserScript==

(function () {
     var msgElem = document.querySelector(".signin-content > h4");
     var msgText = msgElem.textContent;
     var writeRequired = ["update", "\u66F4\u65B0"].some(function (w) {return msgText.indexOf(w) !== -1});

     if (!writeRequired)
         return;

     function p(text, style, _p) {
       _p = document.createElement("p");
       _p.textContent = text;
       _p.setAttribute("style", style);
       return _p;
     };

     var caution = document.createElement("div");
     caution.setAttribute("style", ['-moz-border-radius : 3px'
                                   ,'border-radius      : 3px'
                                   ,'padding            : 10px'
                                   ,'margin             : 10px'
                                   ,'background-color   : #fbd71c'
                                   ,'-moz-box-shadow    : 0px 0px 3px #353535'
                                   ,'-webkit-box-shadow : 0px 0px 3px #353535'
                                   ,'box-shadow         : 0px 0px 3px #353535'
                                   ,'text-align         : center'
                                   ].join(';'));

     caution.appendChild(p("CAUTION", "color : #000000; font-weight : bold; font-size : 40px;"));
     caution.appendChild(p("This application is requesting a 'Write' access", "color : #000000; font-size : 20px;"));

     msgElem.parentNode.insertBefore(caution, msgElem.nextSibling);
 })();