Intermediate drag events stops being fired on Linux

(Needinfo from 2 people)



a year ago
a year ago


(Reporter: tobia.conforto, Unassigned, NeedInfo)


52 Branch

Firefox Tracking Flags

(Not tracked)




a year ago
User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0
Build ID: 20170330203839

Steps to reproduce:

Sometimes during an HTML5 drag & drop operation, the intermediate events (drag, dragexit, dragenter, dragleave, dragover) stop being fired for no apparent reason, even as the user is still dragging the item.

The final events (drop, dragend) are still fired at the end of the operation.

This happens (randomly?) while dragging items inside a single document, but can be easily reproduced by dragging something out of the document and then into it again. (eg. dragging something out of an iframe, and then back into the same iframe, does not resume the intermediate events.)


Actual results:

On Firefox on Linux, intermediate drag events suddenly stop being fired.

Expected results:

On Mac and Windows, as well as on other browsers, intermediate events keep being fired as long as the user is dragging the item.


a year ago
Component: Untriaged → Event Handling
OS: Unspecified → Linux
Product: Firefox → Core
Hardware: Unspecified → x86_64
Flags: needinfo?(michael)
I know very little about the platform side of things and wouldn't know what's going on here without spending a lot of time investigating. 

Is this a regression, or something which has been a bug for a while?

NI?-ing Neil who might know more.
Flags: needinfo?(tobia.conforto)
Flags: needinfo?(michael)
Flags: needinfo?(enndeakin)
Could be the same as 1256952. You could update and try the patch there to see if it helps.
Flags: needinfo?(enndeakin)

Comment 3

a year ago
I don't understand. I'm trying right now and it doesn't show the bug anymore. I'm pretty sure 6 days ago, when I reported this bug, the example failed to work on two distinct Linux machines, mine and that of a colleague of mine.

Comment 4

a year ago
I also affected by this bug. Some sites ( for example) rely on intermediate drag event. Firefox 53.0; Gentoo. Enabled USE flags: dbus gmp-autoupdate hwaccel jemalloc pgo pulseaudio startup-notification system-harfbuzz system-icu system-jpeg system-libevent system-libvpx system-sqlite
Flags: needinfo?(alekseichubukov)

Comment 5

a year ago
Another way to reproduce this bug is to drag second green box on this page
You need to log in before you can comment on or make changes to this bug.