在命令行运行如下命令：
1. 查看当前设置：
gsettings get org.gnome.shell.extensions.dash-to-dock click-action
默认是：‘focus-or-previews’。
2. 查看可设定值：
gsettings range org.gnome.shell.extensions.dash-to-dock click-action
可设定值如下：
enum
'skip'
'minimize'
'launch'
'cycle-windows'
'minimize-or-overview'
'previews'
'minimize-or-previews'
'focus-or-previews'
'quit'
3. 设置为'minimize-or-previews'，就可以实现再次单击使窗口最小化：
gsettings set org.gnome.shell.extensions.dash-to-dock click-action minimize-or-previews