How to reproduce:
- Use ubuntu 23, I think it can be any hardware platform (I use i7-11700K+NVIDIA)
- Turn on the computer without plugging in the monitor, wait for a certain period of time, and then plug in the monitor after the login interface is expected to appear.
- Enter the password and press Enter. At the moment of entering the desktop, the screen is abnormal.
I looked into it and found that the Background Pixmap created by the root window is the default size provided by a driver when there is no monitor. But when plugged into the monitor. The size of the root winddow changes, but the size of the Background Pixmap does not change, so it causes an exception.