How do I keep the panels open? (auto-collapsing option is turned off)

Hi,

A while ago, I have watched a tutorial that was giving a " tip/shortcut" to have the panels collapse when using another panel.

As I don't work on a big screen, at that time I found it useful and used the shortcut.

After using this setting for a while, I would like now to reverse it and have all the panels open at once but I cannot find the shortcut in my notes..

Reseting the workspace does not change it back and the the "auto-collapsing" option in the Preferences is off.

Does anyone know the shortcut I am refering to and how to get back to have all the panels open?

Thank you in advance.

Miyuki