The desktop mouse-drag handlers were bound to the moving <img>, so the
cursor crossing the (transition-lagged) image boundary fired onMouseLeave
and repeatedly aborted/restarted the drag — the flicker. Touch was fine
because it tracks on the full-screen container.
Track the drag on `window` while dragging (mirroring the touch path),
disable the transform transition during the drag so the pan is 1:1, and
set will-change: transform (the transform-gpu class is overridden by the
inline transform, so its GPU hint was lost).
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Huang Xin
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