Toggle side bar on and off with button on front end?

Hi SI Team

Honestly I do not know if I read this in one of your Blog posts or not.

But was there at some point a feature announced that allowed users to “toggle” a side bar on and off.
i.e. set something in the back end so that a button appears allowing users to display the side bar or not!?!
An example being a page displaying videos and being able to hide Video categories listed to the left of the videos.
Maybe it was just in connection with the mobile template.
Maybe I am just imagining this.

hope that this is some how clear for my side

best

Paul