"Some screens scroll sideways, some don't" had two causes, and both were a
number that was right on one monitor.
The lanes. _KanbanColumn set a 150px floor with a comment claiming seven of
them fit a 1280 window; measured, the row wanted 1242px where 1280 leaves 1091,
so a 1280 screen scrolled and a 1920 one did not — this machine has one of each.
The floor is gone. The seven lanes share the board through the layout's
stretch, which is a proportion of whatever width there is, and the only pixel
question left — how narrow before scrolling beats squeezing — is answered from
the font: eight characters of a title plus padding, so it holds at 125%/150%
scaling too. No horizontal scroll now at 1280×720 through 1936×1048, at three
rail widths each, including the rail dragged to its maximum.
Each lane also grew its own scrollbar: QListWidget's column hint runs 1-6px past
its viewport, and which lanes overflowed changed with the window width — 36 of
38 widths had at least one. Cards word-wrap, so there was never anything to
reach sideways; the bar is off.
The rail. Its 360px ceiling was a quarter of a 1440 screen and more than that of
a 1280 one. It is now 22% of the window, capped at 360 — and recomputed on
resize, which is its own bug fixed: read once at construction off a not-yet-sized
window, it sat at 162px on every monitor, so the handle barely moved.
check_kanban_scroll covers five screen sizes × three rail widths. A rail dragged
to maximum on a 1280 screen still scrolls the board — that is the user's own
trade, so it is reported rather than failed.
19/19 checkers pass.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
