I'm using "GNOME Terminal 3.26.2 Using VTE version 0.50.2 +GNUTLS", from Debian testing's "gnome-terminal 3.26.2-2" package, under X.org 1.19.5 (not Wayland).

In most gnome apps, when I do a two-finger scroll on the touchpad, or when I use my trackpoint to scroll, I get a smooth continuous motion. (This is "pixel-wise scrolling", where the actual motion of my finger determines the exact amount of scrolling, as enabled by XInput 2.1.)

In gnome-terminal, this used to work the same way. But something changed: now, when I try to do smooth scrolling up and down, the text moves smoothly for a few moments and then does a discrete jump; if I keep scrolling then this repeats over and over. The overall effect is jerky and disconcerting -- the major advantage of smooth scrolling is that it makes it easier for your eyes to keep track of where things are as they move, but these constant jumps break that.

Reproduction:

- open gnome-terminal
- run 'ls' or something to create some scrollback
- place two fingers on a touchpad with two-finger-scrolling enabled, and move them slowly

Expected result:

- the text scrolls smoothly, as in other GNOME applications like evince or nautilus

Actual result:

- the text alternates between scrolling smoothly and "jumping"

I can make a screencast to demonstrate if this description isn't clear, but on my system it's pretty obvious and seems to reproduce 100% of the time.