674807 - dragexit event doesn't always fire

Status: RESOLVED WONTFIX

(Core :: DOM: Copy & Paste and Drag & Drop, defect)

Description

[Jonathan Kamens]

In an add-on I'm working on, I'm putting a dragexit event on the treechildren node within the folderTree vbox in thunderbird:

    var treechildren = document
	.getElementById("folderTree")
	.getElementsByTagName("treechildren")[0];
    treechildren.addEventListener("dragexit", me.onDragExit, false);

Right now, all me.onDragExit does is log a message indicating that it was called.

If I move the mouse into and then out of the tree slowly while dragging, I see the message indicating that onDragExit was called. If, however, I move the mouse out of the tree quickly, at least half the time the handler does not get called. It subsequently gets called if I move the mouse across another element boundary, or when I release the drag.

An unreliable dragexit event is highly sub-optimal. It's going to make my add-on somewhat flaky.

Comment 1

[Jonathan Kamens]

This gets worse, although perhaps the following should be a separate bug and not the same bug as the one above... As far as I can tell, if I register event listeners for dragexit, dragdrop, mouseup, and mouseout on the treechildren node, then I get a dragexit event if the user lets go of the dragged item without dropping it (e.g., by trying to drop it into the folder it's already in, or by dropping it outside of the folder pane so no folder is selected), but if the user does actually drop it into a folder, then *none of the events above is triggered*, i.e., my code does not get notified by *any* event that the drop has completed.

This makes it very difficult for my add-on to properly finish up the work it's trying to do when the user finishes a drop.

It seems to me that either dragexit should always be sent, regardless of whether the drop was completed, or dragexit should be sent when the drop is aborted or dragdrop if it is completed.

Add-on code needs to have *some* way of saying, "Let me know either way, whether the drop is aborted or completed."

Comment 2

[Kagami Rosylight [:saschanaz] (they/them)]

Attachment: Bug 674807 - Part 1: Disable dragexit event on Nightly r=edgar

Comment 3

[Kagami Rosylight [:saschanaz] (they/them)]

Attachment: Bug 674807 - Part 2: Replace dragexit with dragleave in browser/ r=gijs

Depends on D121189

Comment 4

[Kagami Rosylight [:saschanaz] (they/them)]

Attachment: Bug 674807 - Part 3: Remove redundant dragexit listener from browser/base/content

Depends on D121190

Comment 5

[Kagami Rosylight [:saschanaz] (they/them)]

Attachment: Bug 674807 - Part 4: Replace dragexit with dragleave in devtools/

Depends on D121191

Comment 6

[Kagami Rosylight [:saschanaz] (they/them)]

Attachment: Bug 674807 - Part 5: Replace dragexit with dragleave in editor/libeditor/ r=masayuki

Depends on D121192

Comment 7

[Phabricator Automation]

Comment on attachment 9233689 [details]
Bug 674807 - Part 1: Disable dragexit event on Nightly r=edgar

Revision D121189 was moved to bug 1635018. Setting attachment 9233689 [details] to obsolete.

Comment 8

[Phabricator Automation]

Comment on attachment 9233690 [details]
Bug 674807 - Part 2: Replace dragexit with dragleave in browser/ r=gijs

Revision D121190 was moved to bug 1635018. Setting attachment 9233690 [details] to obsolete.

Comment 9

[Phabricator Automation]

Comment on attachment 9233691 [details]
Bug 674807 - Part 3: Remove redundant dragexit listener from browser/base/content

Revision D121191 was moved to bug 1635018. Setting attachment 9233691 [details] to obsolete.

Comment 10

[Phabricator Automation]

Comment on attachment 9233692 [details]
Bug 674807 - Part 4: Replace dragexit with dragleave in devtools/

Revision D121192 was moved to bug 1635018. Setting attachment 9233692 [details] to obsolete.

Comment 11

[Phabricator Automation]

Comment on attachment 9233693 [details]
Bug 674807 - Part 5: Replace dragexit with dragleave in editor/libeditor/ r=masayuki

Revision D121193 was moved to bug 1635018. Setting attachment 9233693 [details] to obsolete.

Comment 12

[Kagami Rosylight [:saschanaz] (they/them)]

We want to remove dragexit, so I think this is wontfix.