Or whatever the key shortcut is that puts gnome-terminal in "read only" mode, that I kept doing by accident for years, before I found out how to undo it (right-

Or whatever the key shortcut is that puts gnome-terminal in "read only" mode, that I kept doing by accident for years, before I found out how to undo it (right-click, toggle "read only"), thinking it was an obscure gnome-terminal bug.