Expanding / Collapsing Panels

[Snosrap]

I would love it if Illustrator would collapse the panels to a flush right relationship to the screen or working environment. I thought they used to do this.

[Monika Gause]

You mean when you don't need them?

 It's a preferences setting to auto-collapse them.

[Bill Silbert]

If you have all of your panels set up on the right sife of the screen and linked together all you need to do is click on the double arrow of the top right panel (see highlight in left side of picture below). When you click on that then the panels will collapse as in the right side of the screenshot.