User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729) Build Identifier: 4.0b7 Move the mouse cursor to the left menu table, the popup menus will slow down the firefox window. However, before 4.0b1 or previous version, it is correct. Reproducible: Always Steps to Reproduce: 1.open this page 2.move mouse cursor to the left menu table 3.wait a few seconds 4.before leave this page, it will happen again. Actual Results: There is not any waiting for this page. Please refer to 4.0b1 or previous version, or any versions of MS I.E.

confirming with SM trunk (get a slow script warning) and FF4.0b6 on win32 I will try to find a regression range

Last good nightly: 2010-07-14 First bad nightly: 2010-07-15 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=1a107c990c 89&tochange=5355f245b916

So... Are you sure about that pushlog range? I get the day after that: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=5355f245b916&tochange=5fda39cd703c And unlike your range, mine has a tracemonkey merge in it, and the hang is in js engine code according to my profiler. I'll see if I can bisect on tracemonkey.

I'm sorry, I was in hurry because i had to go to work and I couldn't verify the range manually. I used the regression.py script the first time and it seems to cause a off-by-one error on my installation. I need apparently a break from this QA work :-(

Hmm. Bisect says: The first bad revision is: changeset: 46291:dd6799cad9a4 user: Blake Kaplan <mrbkap@gmail.com> date: Mon Jun 28 16:39:00 2010 -0700 summary: Bug 574517 - Separate the inner and outer windows' JS classes. r=jst Also, it looks like the broken builds have this error: JavaScript error: http://www.pconline.com.cn/ssi/js/bjk/index.html, line 259: c.apply is not a function which working builds seem to not have....

Can we get some qa support and capture the page?

Mouse over the text and it should hang. Mozilla/5.0 (Windows NT 6.1; rv:2.0b7pre) Gecko/20100927 Firefox/4.0b7pre

This worksforme. Please re-open if you still see this.