I experienced the same issue on my Dell XPS 13 (9350) running Kubuntu 18.10 (4.18.0-25-generic), KDE Plasma 5.13.5. My laptop was connected to the 2nd monitor using the VGA port on the Dell 4-in-1 adapter with the DisplayLink driver 5.2.14
After rebooting, the mouse no longer flickers when connecting to the 2nd monitor using the DisplayLink adapater so it could be a solution for this problem.
I experienced the same issue on my Dell XPS 13 (9350) running Kubuntu 18.10 (4.18.0- 25-generic) , KDE Plasma 5.13.5. My laptop was connected to the 2nd monitor using the VGA port on the Dell 4-in-1 adapter with the DisplayLink driver 5.2.14
I followed the comment in this link (https:/ /github. com/DisplayLink /evdi/issues/ 29#issuecomment -479529359) and mannually added /usr/share/ X11/xorg. conf.d/ 21-displaylink. conf file with the content below:
Section "Device"
Identifier "DisplayLink"
Driver "modesetting"
Option "PageFlip" "false"
EndSection
After rebooting, the mouse no longer flickers when connecting to the 2nd monitor using the DisplayLink adapater so it could be a solution for this problem.