Missing layout inspector left and right detail pane of Android Studio 2.2 preview 2/3/4/5

Question

I upgraded Android Studio 2.2 preview 2 recently but somehow the left and right detail pane (circled below) of layout inspector is missing. How can I make them appear again? Is it a bug of Android Studio?

The tool windows snaphot when I open an .li file:

Updates 20160609:

Android Studio 2.2 preview 3 still got this problem.

Updates 20160705:

Android Studio 2.2 preview 4 still got this problem.

Updates 20160715:

Android Studio 2.2 preview 5 still got this problem. As reported by a member below.

Answer 1

The bug is already tracked officially.

EDIT (I don't actually believe this, but that's the way it is)

The bug is fixed in Preview 5. The reason why you still don't see the additional panels is because they are shrunken to size 0. Check the following demo video: https://vid.me/ZRKv

Thanks Mattia and Mario

[...] Unfortunately, this won't be in until 2.2 Preview 4.