添加在窗口左侧：

gsettings set org.gnome.settings-daemon.plugins.xsettings overrides "{'Gtk/DecorationLayout': <'minimize,maximize,close:'>}"

 

添加在窗口右侧：

gsettings set org.gnome.settings-daemon.plugins.xsettings overrides "{'Gtk/DecorationLayout': <':minimize,maximize,close'>}"

 

参考：

ELEMENTARY OS 添加窗口最小化按钮