236910 - Elements with overflow:auto and clip: are damaged when scrolled.

Status: VERIFIED FIXED

(Core :: Web Painting, defect, P2)

Description

[:aceman]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7a) Gecko/20040128 Firebird/0.8.0+
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7a) Gecko/20040128 Firebird/0.8.0+

See the URL with testcase and description (Not mine!)

Reproducible: Always
Steps to Reproduce:
See the testcases.
Actual Results:  
The upper part of the content is lost when scrolled.

Expected Results:  
Look what IE does since 5.5. The top of the content should hide when scrolled
and then reappear when the scrollbar is moved to the top.

Comment 1

[:aceman]

Attachment: Another testcase - mine:)

Comment 2

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Attachment: fix

The problem is that nsContainerFrame::SyncFrameViewGeometryDependentProperties
was incorrectly setting SetHasUniformBackground(PR_TRUE) on the scrollport. The
background is in fact not uniform across the whole viewport because the
scrollframe is clipping the background. The fix is to add a check to see
whether the background is clipped (as the original comment actually suggested
should be done...)

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Comment on attachment 144938 [details] [diff] [review]
fix

r+sr=dbaron, although probably applying to only absolutely positioned elements
should be enforced in nsRuleNode rather than at the callers

Comment 4

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Comment on attachment 144938 [details] [diff] [review]
fix

This is very low risk. At worst we could slow scrolling down at places where we
shouldn't.

Comment 5

[chris hofmann]

Comment on attachment 144938 [details] [diff] [review]
fix

a=chofmann for 1.7

Comment 6

[Robert O'Callahan (:roc) (email my personal email if necessary)]

checked in.

Comment 7

[:aceman]

Verified with Firefox 20040423. Thanks.