1400631 - browser.tabs.move() has unexpected behavior when moving tabs within the same window where tab positions are less than insertion point

Status: NEW

(WebExtensions :: General, defect, P3)

Description

[u462496]

When tabs are moved within the same window:

Tab(s) with _tPos's > insertionPoint are inserted at insertionPoint - expected behavior.

Tab(s) with _tPos's < insertionPoint are inserted at insertionPoint + 1 - not expected behavior.

Comment 1

[Eric Promislow]

I filed a duplicate/invalid bug on this at https://bugzilla.mozilla.org/show_bug.cgi?id=1464753

I ran into this while implementing drag/drop in tabhunter, and noticed not only the
obvious off-by-one error reported here as well as in other bugs, but I've observed
some symptoms that point to statefulness. Say I've got tabs [t1 t2 ... t10] and
try to move tabs [t2 t3 t4] targeting t7.

Expected:                   [t1 t5 t6 t2 t3 t4 t7 ... t10 ]
First 1-2 times observed:   [t1 t5 t6 t7 t2 t3 t4 t8 t9 t10 ]
*Sometimes* later observed: [t1 t5 t6 t7 t2 t8 t3 t9 t10 t4 ] -- off-by-one errors build up incrementally

I filed a new bug because I wrote a mini-extension that lets me test the different tab-moving scenarios
and different ways to move the tabs interactively.  But I just discovered YUKI's tests at
https://bugzilla.mozilla.org/show_bug.cgi?id=1394477 and will have a look

Comment 2

[Firefox Bug Husbandry Bot]

Bulk move of bugs per https://bugzilla.mozilla.org/show_bug.cgi?id=1483958