On my PC, I had a Hot-Corner with the action to open activities menu. The dock showed up only when I open the activities, and I liked that. Recently, I had problem with my display manager (which I will not relate here) and it needed me to reinstall GNOME. After this, the display-manager issue is resolved but now the dock shows up on my desktop. Is there a way to hide it on the desktop and show it only in the activities menu? Thank you in advance.
EDIT
How it is now:
Here is where I want it to be:
to use plain gnome (not ubuntu version)
You probably installed the GNOME desktop. To restore the previous experience, you will have to reinstall the Ubuntu Desktop package. Open a terminal and enter the command
Then, choose Ubuntu (not GNOME) session in the login screen.
Image source