Don’t bother using this app, just use the web page.
I’ve experienced that once I down loaded the app onto my MacBook Pro Retina with Yosemite, getting the app to simply work was a challenge. I start the app and then when I switch to another app, I can’t swithc back to the Facebook app. I tried the Alt-Tab, re-opening the app, and closing everything else. The Facebook login app just simply disappeared. It only appears again when I bounce the laptop and start the Facebook app.
Terrible app - did they even test it on Yesomite?