activities-overviewgnome-shellwindow
I'm from Ubuntu GNOME 16.04 and I just installed Ubuntu 18.04 which contains GNOME by default, but there are a lot less preferences.
I want to open the selection of windows (as if we clicked on the 3 points or "Activities" button) but only when my mouse is in the (top-left) corner of my screen.
How can I do this?
Yes it is possible with this Overview all windows extension.
Although it won't work after install, download the schemas folder from its git repo and paste in extension folder.
Path of extension folder:
~/.local/share/gnome-shell/extensions/OverviewAllWindows@amiller27
Overview shortcut will be super+ctrl+tab.
The button next to "Activities" is called "App Menu".
App Menu can be designed to contain not just "close" option, but other options related to the corresponding application, e.g. Preferences/Settings, Help, About etc. But almost all the third-party applications (if not all) are not yet designed to contain any options other than close. If you run native GNOME applications like Files (aka Nautilus), Text Editor (aka Gedit) etc. you'll find there are options other than close.
To remove App Menu from the top-bar you may use (GNOME) Tweaks. First install it by running
sudo apt install gnome-tweak-tool
Then launch Tweaks, go to "Top Bar" section and toggle off the "Application Menu" option.
Best Answer
First install (GNOME) Tweaks by running
Then launch Tweaks and enable the "Activities Overview Hot Corner" option under "Top Bar".