具体问题可参考以下网站：
https://unix.stackexchange.com/questions/196541/remove-disable-hot-corner
https://askubuntu.com/questions/1065973/how-can-i-remove-this-applications-icon-which-does-nothing-on-clicking-either
ubuntu18.04 左上角hot corner 禁用
原文：https://www.cnblogs.com/aoeuy/p/9596060.html
