Today, we are publishing few bookmarklets which will help you to test your pages in different screen resolutions from same browser window. Just drag the required links from below list to your browser toolbar and start testing. After opening the page, click on the required bookmarklet to open the page in a new window with the required dimensions.
If you need help installing these bookmarklets, please check the instructions provided at http://www.scholar.com/bookmarklet.dobbb and http://www.jeteye.com/bookmarket.html