I'm using CentOS 7 with GDM/GNOME 3 on a Dell laptop. I'm using the kmod-nvidia drivers with Bumblebee to support the laptop's Optimus capabilities.
In the graphical environment starting from the greeter, I constantly see a small artifact - a black rectangle the size of a terminal character with the small flashing underline of the terminal cursor. This appears near the top of its screen, usually but not always at the top-left corner. It appears regardless of whether the Nvidia GPU is enabled or whether the Bumblebee daemon is running.
Anyone seen this before? How can I begin to troubleshoot it?