touchpad still registers movement when the laptop lid is closed
I use an external monitor, but when I close my laptop, the touchpad seems to still register movements, so the mouse cursor keeps doing little jumps. My workaround for now is to jam a little card or paper in atop of the touchpad, but that's not really an awesome experience. Owen suspected it might be mutter, might be libinput, or possibly gnome-setting-daemon, so starting here.