Wow, so many replies!
Thanks a lot!
Nobody has a clue? No one knows about modernizr? I thought if it is not documented how to use it with apex, at least those who have dealt with the development of APEX 4.2, can give me an answer.
How you figured out where it is used in Apex 4.2?
Edit an Apex Application Page and Start Adding a Page Item to one of its regions. The very first page of the wizard shows the available Item Types. At the bottom of this page you have a small Select List with a Label Show Unsupported: No/Yes. Of course, you see it when you run Application Builder from a non-CSS3 /non-HTML5 browser like IE8.
That is where Apex 4.2 has used Modernizr to find out that the CSS3/HTML5 feature is not supported/supported in your browser.
Do I as developer need any function calls of modernizr or anything else for older browser versions, that not supports HTML5 and CSS3?
Modernizr.js has no API that the user is expected to call. It does its work on page load and that is it.
Inspect your Apex page HTML DOM with FF/Firebug and search for no-<CSS3 Property> in class of elements. If you find any you say "Modernizr was here!".
Please read this article to understand how Modernizr works.
Modernizr is a library that is included with APEX 4.2 that you can call within your own applications so you can use feature detection and develop workarounds for browsers that do not support a particular html5 or css3 feature. Theme 25 includes Modernizr by default so that developers can begin to use it without taking any additional action. However, as Prabodh pointed out, including the library does not alter your page's UI or functionality in anyway other than adding classes to the HTML tag.
You can learn all about modernizr from their official website at http://modernizr.com
Edited by: ShakeebR on Nov 29, 2012 6:45 AM