Reset .card-columns vertical scroll on drag end (#2964) - #3004
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After dragging a card, empty columns' "Drag cards here" drop zones can peek out at the bottom of the board and push the column headings up, leaving the board stuck until a full page refresh (basecamp#2964). .card-columns is overflow-y: hidden, so it is never meant to scroll vertically. But empty columns' blank-slate placeholders hang past its bottom edge (clipped by the hidden overflow), and the container is still scrollable by browser-internal scrolling such as drag auto-scroll, which some Chrome/Edge builds trigger. Once scrollTop is offset it is never reset, so the clipped slates become visible and the board is stuck. Pin scrollTop back to zero in dragEnd. Since overflow-y: hidden means there is never a legitimate vertical scroll, this is always safe and unsticks the board regardless of what offset it. Closes basecamp#2964.
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Pull request overview
This PR addresses an environment-specific board “stuck” state after drag-and-drop by forcibly resetting vertical scroll on the .card-columns container at the end of a drag. This hardens the drag lifecycle against browser-internal/programmatic vertical scrolling, which is not a supported interaction because the container is overflow-y: hidden.
Changes:
- Reset
scrollTopto0indragEndto prevent empty-column drop zones from peeking out and shifting headings after a drag. - Document the rationale inline, tying the behavior to
overflow-y: hiddenand issue #2964.
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Problem
After dragging a card, empty columns' "Drag cards here" drop zones can peek out at the bottom and push the column headings up, leaving the board stuck until a full page refresh (#2964).
Root cause
.card-columnsisoverflow-y: hiddenbut still a scroll container. Empty columns' blank-slate placeholders hang past its bottom edge (clipped by the hidden overflow), and browser-internal scrolling (e.g. drag auto-scroll on some Chrome/Edge builds) can offsetscrollTop, which is never reset.Fix
Reset
scrollTopto0indragEnd. There is never a legitimate vertical scroll, so this is always safe.Testing
Verified on the dev board: after a drag,
document.querySelector(".card-columns").scrollTopis0. Forcing the stuck state (scrollTop = 9999) then dragging any card snaps it back and unsticks the board.Closes #2964.
screenrecording-2026-07-28_20-42-56.mp4