Dragging a selection of forty photographs onto a collection filed one.
Selection mode reports every press as a ctrl-press — deliberately, so
touch and pointer go through one set of rules rather than two — and ctrl
toggled. So the press that took hold of one of the forty took it *out*
of the selection on the way down. `drag-started` then looked at the cell
under the finger, found it unselected, and did exactly what it is meant
to do with an unselected cell: made it the whole selection and carried
it alone. The only sign was the grabbed cell's ring blinking out at the
moment the user began to move.
A plain press has never had this problem, because pressing an
already-selected cell has always been documented to leave the selection
alone — for precisely this reason. Ctrl now does the same: adding still
happens on the press, since the drag reads the selection immediately,
but *removing* is handed back as `Press::Deferred` and applied by the
click. Slint reports a click only for a press that stayed within
`tap-slop`, so a tap still toggles and a drag never does.
The unit tests now go through a `click` helper — a press and the release
that follows it — because that is the only thing a user can perform, and
calling `apply_press` alone would assert against half the policy.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
dtourolleandClaude Opus 5
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