[Webkit-unassigned] [Bug 19858] New: Text movement leaves blue pixel trail

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=19858

           Summary: Text movement leaves blue pixel trail
           Product: WebKit
           Version: 526+ (Nightly build)
          Platform: Macintosh
               URL: (test case reduction coming)
        OS/Version: Mac OS X 10.5
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P2
         Component: Text
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: kiel.oleson at nanonation.net


Moving some text to the right using JavaScript (in particular, jQuery, though
maybe others) causes a trail of blue pixels to appear to the left of the moved
text.  The trail only appears when certain letters are at the beginning of the
line - for example, if T is the first letter of the line, the blue pixels
appear; if F is the first letter, no extra pixels are visible.  The extra
pixels are in line with the top of the T character when that is the beginning
of the line.    Because these blue pixels are visible when the background is
dark, but not when it is light, it would seem sub-pixel AA is causing issues
here.  When focus is taken from the window, the blue pixels disappear, and
returning focus does not return the pixels.

This bug is reproducible using various fonts (Agenda Light and Lucida Grande
tested) and on Windows and Mac OS.  Windows build tested was Apple's shipping
Safari 3.1.2 under Windows XP; Mac OS build tested was WebKit nightly r34824
under Mac OS X 10.5.4.  Bug was also present in previous Mac OS nightly builds
over the past month or so.


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