Hide activities button and show all running windows in an overview when clicking the 'Expose' icon on the upper right corner. Based on 'Launch and Expose' extension. To disable top left hot corner use 'No Topleft Hot Corner' — https://extensions.gnome.org/extension/118/no-topleft-hot-corner/ .
Note: Binary files aren't shown on the web site. To see all files, please download the extension zipfile.
Expose