Question: must have gnome shell extensions?
Answer: Dash to Dock. Dash to Dock is a fantastic Gnome Shell extension which will provide highly configurable dock. ... 
Dynamic Top Bar. Everybody wants to customize their top bar on Ubuntu Gnome Desktop. ... 
Pomodoro Timer. ... 
Caffeine. ... 
Clipboard Indicator. ... 
Workspaces to Dock. ... 
Refresh Wi-Fi Connections. ... 
Auto Move Windows.