537563 - A second mouse up event gets corrupted if an XmlHttpRequest is done while handling the first one

Status: RESOLVED DUPLICATE of bug 636171

(Core :: DOM: Events, defect)

Description

[turunen]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/532.0 (KHTML, like Gecko) Chrome/3.0.195.38 Safari/532.0
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.6) Gecko/20091201 Firefox/3.5.6

If two mouse buttons are pressed down and then released at the same time, there will be two mouseUp consecutive events for in which event.which == 1, if the mouseUp handler has a synchronous XMLHttpRequest in it. Having an asynchronous XMLHttpRequest doesn't cause the same behaviour. I'm not sure how relevant the usage of XHR is here, but at least this can't be reproduced by replacing the XHR with a delay loop.

Reproducible: Always

Steps to Reproduce:
1. Go to http://puuh.org/~elpuri/mousebug.html
2. Push both mouse buttons down over the white square and release both of them as simultaneously as possible. Might need some repetition.
3. See the output below the square. 
Actual Results:  
Quite often you will see "Left up Left up" (with the latter one highlighted red) where the latter one should of course be "Right up". 

Expected Results:  
There should be a "Left up Right up" or "Right up Left up" sequence every time the mouse buttons are released.

Reproducible at least on Windows 7 and Windows XP SP3.

Comment 1

[turunen]

Step 2 should say "red square" instead of "white square".

Comment 2

[Ria Klaassen (not reading all bugmail)]

Regression range: 
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=b007a5dd8084&tochange=6eeeb369281a
Must say that it is not 100%. Also in older builds you get sometimes one scarce red "Left up" in the page.
But the frequency drastically changed on that date from one to tens.

Comment 3

[Paul Pasca[Away. Please needinfo? Paul Oiegas [:pauloiegasSV]]]

Hi reporter,

The link you provided in comment 0 is no longer available, can you please provide another one so I can test this on my end?

Also, is this still reproducible on your end ? If yes, can you please retest this using latest FF release and latest Nightly build (https://nightly.mozilla.org/) and report back the results ? When doing this, please use a new clean Firefox profile, maybe even safe mode, to eliminate custom settings as a possible cause (https://goo.gl/PNe90E).

Thanks,
Paul.