Multi window supported Android devices (without root) Currently I use Samsung S3 mini with Android 4.1.2. I'm planning to buy an S4 mini or other equivalent small screen phone (HTC One Mini, Xperia Z1 compact).

But I need to use multi-window feature. For example I want to use Twitter and Youtube at the same time. Or Chrome and Facebook from the same screen.

It seems like for S4 mini it is possible with root and Xposed framework. But I need multi-window functionality without rooting.

It seems like Samsung Note 3 and Samsung S4 has this feature.
So which Android used mobile phones has stock multi-window support ?
I'm not absolutely sure, but I believe that that is a feature of Samsung's TouchWiz (proprietary build of Android) and only works select Samsung tablets/phones, among them the Galaxy S5/4, Note 3. The LG G Flex also boasts to have "Dual Window", and LG G Pro 2 has QSlide for limited multitasking.

Other aftermarket Android projects are working on it (OmniROM, ParanoidAndroid) but that still requires a rooted device.

The next best thing are "floating" apps, like Floating Apps (free, $1.99) or Tiny Apps (free, $2.03). These apps create smaller windows that float over all other applications allowing you to interact with multiple apps simultaneously.