Using Lightbox to prevent form double submit

Some month ago I wrote a javascript class that uses a slightly modified version of Lightbox to prevent users to click twice on a form submit button.
The idea is simple: just add a lightbox layer when a user clicks on a submit button and the game is done. This is not an elegant solution, but it works in many cases.
It works also with links that try to call form.submit() method: this class saves previously defined submit functions, creates the layer and then calls old function (if it exists).

var LightboxForm = Class.create();
LightboxForm.prototype = {

yPos : 0,
xPos : 0,

initialize: function(form) {
form = $(form);
form.oldsubmitdoublesubmit = form.submit;
form._lightbox_ = this;

Event.observe(form, 'submit', this.disableWithOverlay.bindAsEventListener(form), false);
form.submit = this.disableWithOverlayJS;
},

uninstall: function(form) {
form = $(form);
form.submit = form.oldsubmitdoublesubmit;
Event.stopObserving(form, 'submit', this.disableWithOverlay.bindAsEventListener(form), false);
},

disableWithOverlay: function(event) {
if(event.returnValue != false) {
this._lightbox_.activate();
return true;
} else {
return false;
}
},

disableWithOverlayJS: function(event) {
this._lightbox_.activate();
return this.oldsubmitdoublesubmit();
},

// Turn everything on - mainly the IE fixes
activate: function(){
if (browser == 'Internet Explorer'){
this.getScroll();
this.setScroll(0,0);
this.hideSelects('hidden');
}
this.displayLightbox("block");
},

// Ie requires height to 100% and overflow hidden or else you can scroll down past the lightbox
prepareIE: function(height, overflow){
bod = document.getElementsByTagName('body')[0];
bod.style.height = height;
bod.style.overflow = overflow;

htm = document.getElementsByTagName('html')[0];
htm.style.height = height;
htm.style.overflow = overflow;
},

// In IE, select elements hover on top of the lightbox
hideSelects: function(visibility){
selects = document.getElementsByTagName('select');
for(i = 0; i < visibility =" visibility;" ypos =" self.pageYOffset;" ypos =" document.documentElement.scrollTop;" ypos =" document.body.scrollTop;" display =" display;" display =" display;" browser ="="">

When the lightbox is activated a div called lightbox is displayed, so if you want provide some information to the user you can define a div using a function like this:

// Add in markup necessary to make this work. Basically two divs:
// Overlay holds the shadow
// Lightbox is the centered square that the content is put into.
addLightboxMarkup: function() {
bod = document.getElementsByTagName('body')[0];
overlay = document.createElement('div');
overlay.id = 'overlay';
bod.appendChild(overlay);

message = document.createElement('div');
message.id = 'lightbox';
message.className = 'leightbox';
message.innerHTML = 'Request sent, please wait...';
bod.appendChild(message);
}

Somewhere in your html page you should put something like:

new PreventDoubleSubmit();

Don't forget to use the right css file. You can get a copy here
You can download a copy of this javascript code here. In this file you will find also a class that provides an hook on onload window event to allow all forms in the current page to be wrapped by the LightboxForm object.

Update 1:
The script relies on prototype.js and uses a script to detect the browser (the script was made from Chris Campbell from ParticleTree).

Update 2: due to some error in this post, the script was not working. I apologies for this: this post was made too quickly in the past.
Now I made a little example on how to integrate the script in your pages. Just download this archive and see the index.html file. It should be quite easy to understand.


Update 3: Thanks to Ken B. I added a simple and nice feature to the script: customizable html message for the submit.
Actually the message showing during submit is controlled by this line: message.innerHTML = 'Request sent, please wait...';.

I changed the source code to let you pass a custom message to the PreventDoubleSubmit object.
So now you can write something like:
PreventDoubleSubmit('

Please wait...

');. Of course, a default message is generated if you continue to use the old syntax.
I updated the script and the example.