Helper in a bottom-positioned Sortable is positioned wrong on drag start

[squeakytoy]

When a Sortable is placed in an absolutely positioned container where the position is set using 'bottom' with all other default settings, the helper is not positioned properly on drag start. It is positioned too high vertically by the amount of the height of the helper. The reason for this bug is that the placeholder has not yet been created at the time that the parent offset is calculated, and the bottom alignment of the list causes the offset to be calculated as a smaller amount.

The fix for this bug is to create the placeholder before the offsets are calculated. Attached is an html file that shows the big reproducible, and a patch to fix the issue.

[squeakytoy]

Patch to resolve issue with helper positioning

[squeakytoy]

Repro of the issue

[squeakytoy]

Ugh, ignore my late-night typos. At least the bug is fixed. :)

[martinf55]

Applied an updated version of the patch fix here: ​https://github.com/martinf55/jquery-ui/blob/971f3011aeb91a51373667475fbf3af35c41d13e/ui/jquery.ui.sortable.js

[martinf55]

Sortable: Moved change of helper position css. Fixed #5321 – Helper in a bottom-positioned Sortable is positioned wrong on drag start.

Changeset: 32f356bbfa9a8f3b90b4e64331e9108b4d87a349

[martinf55]

Sortable: Moved change of helper position css. Fixed #5321 – Helper in a bottom-positioned Sortable is positioned wrong on drag start. (cherry picked from commit 32f356bbfa9a8f3b90b4e64331e9108b4d87a349)

Changeset: 8e899dab6cd1fc410bbda0e7c88cdf1a1c8e9764