copy/paste: On March 10th Facebook will stop supporting its FBML app, and on this day it will no longer be possible to create new FBML-based fan gates. When Facebook officially makes the switch on March 10th from FBML to iFrames there?ll be a lot of great benefits for fan page owners, including greater flexibility in terms of design and functionality. But it does create a pretty major challenge for the hundreds of thousands of fan page owners who?ve relied on Facebook?s FBML app to display a ?fan gate? (otherwise known as a ?reveal tab?) on their Fan page.