[Aetae]

(function () {
d = document;
e = d.createElement('button');
e.style.cssText = 'font-size: 7pt; position: fixed; bottom: 0px; left: 90px; height: 20px; border: 1px solid black; z-index: 2147483647; opacity: 0.5;  filter:alpha(opacity=50);';
d.documentElement.appendChild(e);
e.innerHTML= '<b>Кнопка</b>';
e.onclick = function() {

var message = 'Здравствуй';
alert( message );

}})();