Using the JavaScript API for Connect

FB.Connect.showProfileTabDialog(callback);

This method renders an Add Profile Tab button on your canvas or Web page, enabling the user to add your application tab to his or her profile.

If the user already added your application tab, the button doesn’t appear.

You can determine if a user added your application tab by querying the tab_added field in the permissions FQL table.

The optional Callback function can be used to execute after this call completes. It takes one argument, which is a JavaScript object. The object has one key, tab_added, the value for which is 1 or 0.

Using an XFBML tag

<fb:add-profile-tab />

or, if you’re using Connect

<fb:add-profile-tab></fb:add-profile-tab>

Renders a button that lets a user add your application or site’s application tab to his or her profile. Make sure you specify a Tab Name and a Tab URL in your application settings (on the Profiles tab).

If the user already added your application tab, the button doesn’t appear.

You can determine if a user added your application tab by querying the tab_added field in the permissions FQL table.

The Facebook Platform is down again with the Platform Live Status page all in red. There have also been reports that the entire Facebook network was down as well.
FBML based apps are currently performing the worst and a small subset of canvas apps are not being redirected to their Callback URLs.
It seems that all this happened just after this week’s weekly code-push .

We’ll keep you updated as the situation evolves.

The Facebook Platform has just recovered from about 10 hours of degraded performance.

Application developers were complaining about various FBML related problems from as long as 11 hours ago. 6 hours ago it was almost impossible to access a FBML canvas application. The errors ranged from FBML timezone renders to even basic HTML table renders (which by the way still continue to show for various apps). To reduce these kind of errors we suggest to turn off the canvas quick transitions option.

It is noteworthy to mention that today is Tuesday and the performance issues were directly connected to Facebook’s weekly code-push, which occurs on Tuesdays, and that today’s code-push included the updated stream story structure, where stream stories can contain just 1 image with limited number of lines and a Read More link.