Strange behavior when scrolling rapidly with ScrollbarInSinglePage = true

[ogatatsu]

SumatraPDF version

• Version [pre-release build version 18324]

Describe the bug
When ScrollbarInSinglePage = true, if you scroll strongly and then try to scroll in the opposite direction, scrolling will not occur in that direction.

To Reproduce
Steps to reproduce the behavior:

1. Set ScrollbarInSinglePage = true
2. Scroll down strongly
3. Scroll up
4. Scrolls downward rather than upward

Expected behavior
4. Scroll up

[kjk]

1. There are many ways to trigger scroll. Which one are you using?

2. What view setting? Single page, continuous? Which zoom level?

[ogatatsu]

1. mouse scrolling

2. Fit a Single Page

Perhaps the issue is being postponed to the next event if GET_WHEEL_DELTA_WPARAM returns a value other than 120 (such as 240 or 360)?
This might not be reproducible if you're using a mouse that trims the hid report scroll value to 1 even with high-speed scrolling.

[kjk]

can't reproduce. can't fix things I cannot reproduce