Support Multitasking in iOS 11

[mark4flies]

One of the new features introduced in iOS 11 is the ability to work in two apps that share the iPad screen. You can see multitasking demonstrated in a video here.
I tried to share the HP Prime app with the iBooks app so that the calculator is right alongside the User Guide while I am learning or using it for reference. (Obviously, this ability would be useful whenever you are working in a book or article that requires any computation with the HP Prime.) The feature works in the landscape orientation. With iBooks already active, I tried bringing the HP Prime from the dock to the right side. It failed in two ways: it already switched to landscape and it displaced iBooks as the active app.
I simply switch back and for between my book and calculator now but I have to remember everything from the other app because I can’t see both simultaneously. I know that I can manage iBooks and HP Prime windows easily on macOS to do what I want but I travel a lot for work and usually bring only my iPad with me.
Thanks for considering.