Facebook chatheads not staying up + noti-centre not remaining open



Hi, I have a Nexus 4, stock and all that. For months now, my notification centre does not remain open when I slide it down. And, if I drag it down slowly, it'll glitch out - like it's lost focus. Same with the Facebook Chatheads - I tap one and I have 0 to ~8 seconds to type my message before it closes. It's truly fustrating.
What colud be causing this, and more importantly, how can I fix this issue? :/
Thank you so much!