1555496 - Bookmarks Folder would not open when dragover a link

Status: VERIFIED FIXED

(Firefox :: Bookmarks & History, defect)

Description

[Alice0775 White]

Attachment: screencast

This is regression since Nightly69.0a1

Reproducible: always (first time doesn't happen)

Steps To Reproduce:

1. Enable Bookmarks Toolbar
2. Create a folder in the Bookmarks Toolbar
3. Drag a link to the folder directory(Without going through other bookmark items.)
4. Mouse cursor shape will change to "arrow+small rectangle" from "prohibited mark"
   ---- observe, folder will open or would not open (first time doesn't happen)
5. Cancel drag operation(press ESC key) and Click on elsewhere to close any popup
6. Repeat from step 3

Actual Results:
The folder would not open

Expected Results:
The folder should open

Regression window:
https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=f287bb6c18942c75aca41d54987006951270628d&tochange=c8e9b6a81194dff2d37b4f67d23a419fd4587e49

Regressed by: Bug 1519577

Andrew Swan,
Your patch seems to cause the regression. Can you please look into this?

Comment 1

[Andrew Swan [:aswan]]

Attachment: Bug 1555496 Fix bookmark toolbar drag handlers r=bgrins

Code here explicitly references lastElementChild inside a toolbarbutton
but it doesn't have any tests so it wasn't caught when bug 1519577 landed :(

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/f6eb58afc87b
Fix bookmark toolbar drag handlers r=bgrins

Comment 3

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/f6eb58afc87b

Comment 5

[Gabi Cheta [:Gabi] Desktop QA]

Reproduced the issue on a Nightly from 2019-05-29.
Verified as fixed on 69.0b6 with Windows 10x64, Ubuntu 16.04 and macOS 10.12.6