Middle-Button Scrolling on Pdf Files Causes Smooth/Animated Inertial Scrolling

Distribution

Fedora 40 t2

Package version

4.0.2

Frequency

Quite often

Bug description

If I use a 3-button mouse and middle-button scrolling, then the page continues scrolling after I've stopped scrolling. It takes time o slow down and stop.

Animated scrolling is disorienting, it makes it harder to find your place after scrolling, and it can cause motion sickness.

I'm uing Cinnamon, with Effects turned off, to try to avoid these types of animation.

Steps to reproduce

1. Open a pdf file in xreader.
2. Set it to continuous view; page-by-page view currently breaks scrolling.
3. Hold the middle mouse button and drag up or down for some time. The longer you drag, the more likely you are to encounter the continued scrolling.

Expected behavior

When you release the middle mouse button, it should stop scrolling.

Additional information

This is for the grab scroll option, not for autoscroll.

Xreader has its own built-in grab scroll. In addition, if you use xorg, then xinput set-prop can set global grab scroll. This occurs with the xinput grab scroll disabled (so the xreader version is doing this) or enabled (so either or both may be doing this). From what I've seen, if you use wayland, there is not yet any global grab scroll.

Reproduce the issue in Xreader 4.0.2 using continuous view and the built-in grab scroll with a middle-button drag. Start by locating Xreader's grab-scroll handling and compare behavior with xinput grab scroll disabled and enabled. Done means releasing the middle button stops scrolling immediately without inertial movement.