If you have a website that you maintain, here's some code for you.


<!-- %%%%% Mozilla Setup Start -->
<div id="mozilla_modal" title="[Your Title Here]">
<h1 align="left">[Your Heading Here]</h1>
<p align="left">[Your Message Here]</p>
</div>
<link rel="stylesheet" href="//code.jquery.com/ui/1.10.4/themes/ui-lightness/jquery-ui.css" />
<script src="//code.jquery.com/ui/1.10.4/jquery-ui.js" />
<script>
// Mozilla modal init
(function($){
$("#mozilla_modal").dialog({
height: 370,
width: 400,
modal: true,
autoOpen: false
});
})(jQuery);

$(document).ready(function(){
if (navigator.userAgent.toLowerCase().indexOf("firefox") > -1) {
var cookie_key = "mozilla_show_one_time_panel";
var cookie_match_key = cookie_key + "=";
var cookie_set = "set";
var cookie_val = "";

// Check if the one time cookie has been set
var ca = document.cookie.split(';');
for (var i = 0; ca.length > i; i++) {
var c = ca[i];
while (c.charAt(0) == ' ') {
c = c.substring(1,c.length);
}
if (c.indexOf(cookie_match_key) == 0){
cookie_val = c.substring(cookie_match_key.length,c.length);
}
}

// Set the one time cookie if not already set
if (cookie_val != cookie_set) {
var date = new Date();
date.setTime(date.getTime()+(365*24*60*60*1000));
var expires = date.toGMTString();
document.cookie = cookie_key + "=" + cookie_set + "; expires=" + expires + "; path=/";

$("#mozilla_modal").dialog("open");
}
}
});
</script>
<!-- %%%%% Mozilla Setup End -->


If you're not a techie and you'd like to know what it does, then just go to the Papa Possum blog and find out (you have to be using a Mozilla browser like Firefox to see what the code does).

http://www.papapossum.com

You're welcome.