Disable annoying full screen call notification

So i have a kit-kat 4.4.4 on an xperia z2. all incoming calls show a full screen notification whether i like it or not, even during an non interruptable full screen activity. on iphones and windows phones it is possible to change the full screen mode into a notification on the notifications bar, which will also be possible in android 5 from what i have heard. is it possible to achieve the same in android 4.4? or even if there is any app for that it would be great... note: i prefer not to root my device if its possible. thanks alot in advance guys, this thing can really get on my nerves sometimes, you know when you cant answer but cant hung up either? and just have to wait it out till the call ends...