Bug 63331 - [Async overflow scrolling] Incorrect clipping of fixed element inside overflow element with compositing
Summary: [Async overflow scrolling] Incorrect clipping of fixed element inside overflo...
Status: NEW
Alias: None
Product: WebKit
Classification: Unclassified
Component: Layout and Rendering (show other bugs)
Version: 528+ (Nightly build)
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Nobody
URL:
Keywords: InRadar
: 83190 115377 196145 (view as bug list)
Depends on:
Blocks:
 
Reported: 2011-06-24 10:19 PDT by Simon Fraser (smfr)
Modified: 2022-07-14 19:35 PDT (History)
8 users (show)

See Also:

Attachments
Testcase (1.29 KB, text/html)
2011-06-24 10:19 PDT, Simon Fraser (smfr) 		no flags Details
Another testcase (705 bytes, text/html)
2012-04-20 11:57 PDT, Dean Jackson 		no flags Details
Show Obsolete (1) View All Add an attachment (proposed patch, testcase, etc.)

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Description Simon Fraser (smfr) 2011-06-24 10:19:35 PDT 
Created attachment 98505 [details]
Testcase

Testcase shows incorrect clipping of fixed element inside overflow:scroll element when compositing is enabled. The fixed element should not be clipped.
Comment 1 Simon Fraser (smfr) 2011-06-24 10:59:18 PDT 
The assumption that if an element with z-index has overflow, all its children are clipped by that overflow is false for fixed position elements.
Comment 2 Simon Fraser (smfr) 2011-09-02 10:40:55 PDT 
This is tricky. Overflow get special treatment for positioned elements. I'm going to have to put them outside the clipping layer, and give each their own clipping layer or something.
Comment 3 Dean Jackson 2012-04-20 11:57:11 PDT 
Created attachment 138136 [details]
Another testcase
Comment 4 Dean Jackson 2012-04-20 11:58:29 PDT 
*** Bug 83190 has been marked as a duplicate of this bug. ***
Comment 5 Simon Fraser (smfr) 2013-04-29 14:48:59 PDT 
*** Bug 115377 has been marked as a duplicate of this bug. ***
Comment 6 Radar WebKit Bug Importer 2013-04-29 14:51:36 PDT 
<rdar://problem/13766693>
Comment 7 Simon Fraser (smfr) 2020-04-09 15:03:32 PDT 
*** Bug 196145 has been marked as a duplicate of this bug. ***
Comment 8 Fujii Hironori 2022-07-14 19:16:24 PDT 
Comment on attachment 138136 [details]
Another testcase

The latest Safari has no problem for this test case. It seems another problem already fixed.
Comment 9 Fujii Hironori 2022-07-14 19:18:00 PDT 
STP 148 still has this issue.
Disabling Async Overflow Scrolling Internal Feature setting of MiniBrowser can work around the issue.