Why can't all apps be used in split screen view?

[RG129]

Seems odd that some apps can't be used split screen. If they're not full screen games, I wonder why they can't be shrunken down to half the screen.

 

[dpham00]

The developer needs to put in the coding for it

 

[pinkvikchick]

I know!!!! I wish they all did! Specifically the *&^#^$&* calculator!

 

[bsteppuhn]

^this!!

 

[RG129]

Does the Android N preview allow split screen with all the apps? Or does it require the same code to split?