Follow-up to #45600.
## Summary
Fix mouse scroll reports sending only one event when scrolling down in
terminal apps with mouse mode (tmux, neovim, etc.), regardless of how
many lines were scrolled.
## The Problem
After #45600, trackpad scrolling speed was fixed. But when scrolling
**down** (negative `scroll_lines`), the terminal was still sending only
**one** scroll report per gesture, no matter how many lines the user
scrolled. Scrolling up worked correctly.
## Root Cause
In `scroll_report()` we had:
https://github.com/zed-industries/zed/blob/94851aff196bfb5b91d68cb52fa1502d6b4c5b29/crates/terminal/src/mappings/mouse.rs#L96
`scroll_lines` can be negative (scroll down) or positive (scroll up).
For negative values:
| scroll_lines | max(scroll_lines, 1) | Reports sent | Verdict |
|--------------|---------------------|--------------|------|
| 3 (up) | 3 | 3 |Right
| -3 (down) | 1 | 1 |WRONG|
So we always sent exactly 1 report when scrolling down, losing the
scroll magnitude.
Use `scroll_lines.unsigned_abs()` instead of `max(scroll_lines, 1)`.
This matches how `alt_scroll()` in the same file already handles
`scroll_lines`. Now both directions send the correct number of reports.
https://github.com/zed-industries/zed/blob/94851aff196bfb5b91d68cb52fa1502d6b4c5b29/crates/terminal/src/mappings/mouse.rs#L102
## Testing
- Added unit tests: `scroll_report_repeats_for_negative_scroll_lines`
and `scroll_report_repeats_for_positive_scroll_lines`
- Manually tested scrolling in tmux and neovim with mouse mode
---
Release Notes:
- Fixed mouse scroll in terminal apps (tmux, neovim, etc.) only sending
one scroll event when scrolling down, regardless of scroll amount
Emamul Andalib
0c8811da84