[Galaxy Note 10.1 (2014 Edition) General] Vasishtha:
I'm not sure if this has been pointed out already, but I have found a reddit thread which gives instructions on how to do just that.

I'm running Temasek's android 5.1.1 with the 5.1.x Xposed framework(by romracer) and I'm in complete bliss, I've been freed from the Touchwiz lag wagon!

It's not perfect, some splitscreen bugs here and there, but floating windows are very useable; resizable, moveable, minimizeable.

The Touchwiz alternative isn't perfect either,so...yeah..

The AOSP alternative is actually faster and smoother then on Touchwiz.

My essential apps are perfectly* able to be floated or splitted, these include:

-Chrome, Youtube, Password manager, Note taking, Calculator, email, messaging, office, file explorer, pdf reader.

*most apps are floatable via the recent app screen, however the apps that refuse this action can be forced to comply (float on app open).

Here's the original link: https://www.reddit.com/r/nexus6/comments/2wh9vw/multiwindow_for_the_nexus_6_thanks_to_xposed/ only use the mentioned version ofcourse.

Do's and dont's:

-Don't fiddle around with the 'xHaloFloatingWindow>SystemUI Modes' and/or ',, ,, ,,>Status Taskbars', as it may cause System UI to crash constantly (even if you disable xposed, rooted apps keep crashing).

-more to come.

Some quick settings and tips:

-Set/keep the ',, ,, ,,>Popup Behavior>Whitelist/Backlist options' to default if you wish.

-To force apps into floating mode, add an app to ',, ,, ,,>Popup Behavior>Whitelist Apps'.

-MultiWindowSlidebar is only useful for apps which have been forced into floating mode, any other apps added will be opened in fullscreen (these apps will need to be floated via the recent apps menu).

-unfortunately some apps refuse to open floated(via recents) once they're already opened the normal way, which makes it impossible to open them floated unless you forcefully do so.

Forcing them may or may not be useful. However you don't have to; if you kill the app(via app info screen) and the killed app still shows in recents, you can reopen it in floated(the app is restarted in floated that way, through recents).

There is an even quicker way to achieve this, and I discovered it by accident.

If you're on Tamesek's rom, go to 'settings>Tamesek spare parts>app bar'

Enable it, add you're apps in it.

If you now long press an app in the app bar it'll open in a floating window(some apps must be closed before they can be floated;just close them via recents).

The app bar has in effect replaced my multiwindowsidebar app.

-more to come

Functionality loss compared to touchwiz and/or decrease in reliability:

-no 4 way split screen, only 2 way.

-no app bubbles (these however can be turned on and showed in the notification bar, if you've set the right setting).

-Apps floated via recent's do not get a 'bubble' in the notif. bar if they get minimized. However you can reopen the apps in recents and the apps will reopen themselfs as floated.

-It's not as easy to snap 2 app's side by side.

-Some apps crash/misbehave whereas on TW they wouldn't have.

-Some apps misbehave when forced into float, but do not when it's floated from recents.

Vice versa.

-Split screen divider bar doesn't always show up>Can't resize on the fly.

-Status bar causes some floated apps te misbehave; I use gmd gestures to quickly hide/unhide the bar.

Analyse the relevant behaviors to adapt to them.

-more to come.

All the fluidity of AOSP bundled with most of the functionality of TouchWiz, I highly recommend you try out his instructions. You won't be disappointed, though you will be needing some patience.

Let me know how it went and share your experiences.

-V