[Webkit-unassigned] [Bug 44529] New: beforeload listener causes rendering flash

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=44529

           Summary: beforeload listener causes rendering flash
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Macintosh Intel
               URL: http://cbgb.com/
        OS/Version: Mac OS X 10.6
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P2
         Component: Layout and Rendering
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: drewthaler at mac.com


Created an attachment (id=65283)
 --> (https://bugs.webkit.org/attachment.cgi?id=65283)
screenshots and extension

A highly reproducible rendering flash occurs on http://cbgb.com/ whenever a Safari extension adds a 'beforeload' listener to the page. It doesn't matter what's in the listener; the problem can be reproduced with a trivial empty listener. Removing the listener eliminates the problem.

The site is using jShowoff to rotate through different header images every 8 seconds or so. The initial load of the page is OK, but almost every time the header rotates after that, it will render incorrectly for a fraction of a second as it changes to the next image.

The attached zip includes:
 - header-good.png = screenshot of correct rendering
 - header-bad.png = screenshot of incorrect rendering
 - beforeload.safariextension = source of Safari extension to reproduce the problem
 - beforeload.safariextz = packaged Safari extension to reproduce the problem

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