Facebook messenger popup problem on miui

Hey guys,if any of you have problems with the Messenger app not displaying Chat Heads,follow this
1) Open Security
2) tap 'other permissions'
3)Select Messenger from the list
4)Again scroll down and tap 'Permission Manager'
5)Scroll Down and tap 'Display Pop Up Window'
5)Select 'Accept'
And that's it :)
P.S:- you can do this for any apps which dosent show pop up windows,for eg:Bluelight Filter