Changa should not be the default font because it might deter some people away. Of the available fonts, Nastaleeq3, Sherazde and a few others are same or similar as those generally used in Urdu newspapers; so the default selection should be one of them.

The interface is really easy to grasp though and the default font size (130%) and line-height (180%) are both perfect.

May Allah Ta'ala reward the developer for his efforts.

I like this add-on. I was looking for some way to increase the size of urdu font in facebook and it gets the job done.

Thats one of the kind extension. Thanks for that.
Try adding more fonts, and remove some.
good effort (Y)