android studio designer preview: how to include device frame?

In Android Studio 2.2 and above you can enable and disable designer preview device frame as follows

1- Click on designer preview window

2 - press F button from your keyboard

this will enable and disable the designer preview device frame every time you press F button from your keyboard. this works for me. I hope its work for you as well.

It does not work with latest version of Android Studio 3.1