Karabiner parity: mouse-to-scroll (mouse_motion_to_scroll)

[malpern]

Summary

Karabiner-Elements supports mouse_motion_to_scroll manipulator type that converts mouse movement into scroll wheel events (e.g., hold a modifier and move mouse to scroll). Kanata has no equivalent.

Karabiner Features

• Converts mouse X/Y movement into scroll events
• Supports momentum scrolling
• Configurable speed multiplier
• Can be gated by modifier conditions

Current State

• Kanata: Not supported
• KeyPath: Not supported
• Karabiner converter: Rules using mouse_motion_to_scroll are flagged as unconvertible (Tier 3)

Impact

Niche but valued by trackball and ergonomic mouse users.

Related

• Tracking issue: Tracking: 100% Karabiner conversion fidelity roadmap #213
• Feature matrix: docs/karabiner-converter-feature-matrix.md