I use Arch Linux. When I connect an external monitor to my ThinkPad, the cursor moves erratically on the touchpad. It moves slowly, stutters, doesn’t go where I want it to, or goes past the target. There’s no problem with the mouse. The touchpad doesn’t always cause problems—it happens sometimes, and it’s very frustrating.
I’ve had this happen, I swear it was a ground problem. Does it behave the same if you are plugged into power? Also, is the mouse connected when it’s happening?
What DE/WM do you use? Have you tried replicating the problem on a different one?
KDE Plasma. I have not tried any other. XFCE is too basic and I hate Gnome. Even if it worked without any problem, I don’t think I could use another DE.
You should try a different one to isolate the problem. Is it something specific to KDE or your system more generally.
Might I ask which:
- Which Thinkpad? (CPU model and graphics would be helpful)
- What resolution and refresh rate of monitor?
- What does the trackpoint do during this? I know you said it’s not the mouse, but I’m just curious.
If it’s a modern-ish Thinkpad (like ~2018 or newer), these problems are weird and I have no advice to offer, but if you’re one of those guys who daily-drives a Core 2 Duo Thinkpad, I’m curious how they do when hooked to a 4K monitor.
- Thinkpad E14 Gen 3. 8x AMD Ryzen 3 5300U with radeon graphics.
- 3440 x 1440 (21:9)
- Trackpoint works just as smoothly as mouse.
