729968 - document.documentElement['offsetHeight'] returns an unexpected value equal to one pixel greater than the expected value

Status: RESOLVED INCOMPLETE

(Core :: Web Painting, defect)

Description

[Jesse]

A Firefox 10.0.2 change in behavior compared to Firefox 3.6. This change in behavior breaks functionality that previously worked as expected in Firefox 3.6 and earlier. The behavior change is that a page with its vertical scroll bar positioned at the bottom should evaluate document.documentElement['offsetHeight'] - window.pageYOffset - document.documentElement['clientHeight'] to a value of zero. Firefox 3.6 evaluates the aforementioned equation to a value of zero which is expected and correct. However, Firefox 10.2 evaluates the aforementioned equation to a value of one which is not expected. It is believed that document.documentElement['offsetHeight'] returns a value that is one pixel greater than the expected value which is the cause of the problem. This calculation is used to determine that the Firefox vertical scroll bar is indeed positioned at the bottom which is not possible when document.documentElement['offsetHeight'] returns an unexpected value.

Page that demonstrates the problem:
http://www.quimby.com/dev/bugFF10_offsetHeight.asp

Comment 1

[Alice0775 White]

I can reproduced if HWA turned off. but cannot reproduce with HWA on.
http://hg.mozilla.org/mozilla-central/rev/5e756e59a794
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20120223 Firefox/13.0a1 ID:20120223031236


Regression window,
Cannot reproduce:
http://hg.mozilla.org/mozilla-central/rev/b94cf8147ccd
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.3a1pre) Gecko/20100111 Minefield/3.7a1pre ID:20100111140136
Can reproduce:
http://hg.mozilla.org/mozilla-central/rev/47cd92d616d7
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.3a1pre) Gecko/20100111 Minefield/3.7a1pre ID:20100111150802
Pushlog:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=b94cf8147ccd&tochange=47cd92d616d7
Suspected :
Bug 526394 - Move scrolling out of the view system into layout

Comment 2

[Timothy Nikkel (:tnikkel)]

It seems like it's the window.pageYOffset value that is changing, which would make more sense given the regression window.

Comment 3

[Cosmin Muntean [:cmuntean], Ecosystem QA]

I have tried to test this issue, but it seems that the provided URL is no longer available. Jesse, could you please provide another URL or a test case in order to test this issue?

Also, is this still reproducible with the latest Firefox version on your end?

Comment 4

[Cosmin Muntean [:cmuntean], Ecosystem QA]

Marking this as Resolved: Incomplete due to the lack of response from the reporter.
If anyone can still reproduce it on latest versions, feel free to reopen the issue and provide more information

Comment 5

[BugBot (nomail) [:suhaib / :marco/ :calixte]]

Clearing the needinfo request since this bug has been closed as INCOMPLETE for 10 years, 2 months and 26 days.

For more information, please visit BugBot documentation.