While I sympathize regarding the lack of the feature I often wonder how critical it is on a tiny screen like the Note 4 . . . yes I realize the Note 4 has a large screen but REALLY, once you put two applications on screen there's no room to pull up an on screen keyboard so how far do you end up going before you tap on something to type and all heck breaks loose with regards to limited screen real estate? I'm biased, I carry a Note Pro 12.2 around with me practially everywhere.
BTW to add some usefulness to my response, LOL, there is an alternative to enable more multiwindow "support":
https://forums.androidcentral.com/e...i.xperiacle.multiwindow.enable&token=LssDvQWZ
Using this application one can process installed apps to enable multiwindow support. The program will take the APK files for the app you select, process them (I'm assuming it edits it and recompiles it) and then allow you to reinstall the application which will then give it multiwindow support.
BE WARNED, essentially this is going to take any apps that you process off grid - meaning to say they'll no longer be updated in Google Play Store. So . . if you do it, keep in mind that periodically you'll have to uninstall the app, reinstall from Play Store and reprocess with the multiwindow enabler.
BE WARNED, not all applications will work well using this method. Depending on the application developer and how the app is written sometimes the graphical and text elements will scale properly in a window, other times it won't. It's not the multiwindow enabler's fault, it's the original app developer's.