Bug 58515 - Translucent scrollbars on composited layers render incorrectly
Summary: Translucent scrollbars on composited layers render incorrectly
Alias: None
Product: WebKit
Classification: Unclassified
Component: Layout and Rendering (show other bugs)
Version: 528+ (Nightly build)
Hardware: Macintosh OS X 10.5
: P2 Normal
Assignee: Simon Fraser (smfr)
Depends on:
Reported: 2011-04-13 22:51 PDT by James Robinson
Modified: 2011-09-26 22:11 PDT (History)
3 users (show)

See Also:

testcase (841 bytes, text/html)
2011-04-13 22:52 PDT, James Robinson
no flags Details
Patch (6.46 KB, patch)
2011-09-09 16:22 PDT, Simon Fraser (smfr)
sam: review+
Details | Formatted Diff | Diff

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Description James Robinson 2011-04-13 22:51:03 PDT
See the attached test case.  It appears that when the RenderLayer owning the scrollbars becomes composited we somehow render the translucent scrollbars twice on top of each other or something of the like.  I can reproduce the issue in Chromium, WebKit nightlies, and minibrowser.  The patch on bug 57202 ensures that this bug doesn't happen when the overflow controls are on their own layer, but it doesn't help when the controls are not.
Comment 1 James Robinson 2011-04-13 22:52:15 PDT
Created attachment 89537 [details]

This page has a div with overflow:auto with custom scrollbars set to rgba(0, 127, 0, 0.5).  The div alternates between being composited and not composited every second.  When it's composited, the scrollbar regions appear 'more green' then they should.
Comment 2 Simon Fraser (smfr) 2011-08-29 17:43:39 PDT
Looks like this was cased by https://bugs.webkit.org/show_bug.cgi?id=23740
Comment 3 Simon Fraser (smfr) 2011-09-09 16:22:41 PDT
Created attachment 106935 [details]
Comment 4 Simon Fraser (smfr) 2011-09-26 22:11:34 PDT