[Webkit-unassigned] [Bug 150557] New: REDENDERING -BUG: if two adjacent sides for the <fieldset> element have EXACTLY the same color defined

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=150557

            Bug ID: 150557
           Summary: REDENDERING -BUG: if two adjacent sides for the
                    <fieldset> element have EXACTLY the same color defined
    Classification: Unclassified
           Product: WebKit
           Version: WebKit Local Build
          Hardware: All
                OS: All
            Status: NEW
          Severity: Critical
          Priority: P2
         Component: CSS
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: noel.vellemans at visionbms.com

Created attachment 264045
  --> https://bugs.webkit.org/attachment.cgi?id=264045&action=review
RENDER-bug - simulation files.

I encounter, some RENDERING-ERRORS using webkitgtk-2.4.9 ( or later) and the latest revision in SVN trunk.

In certain pages, I do get faulty-rendered  'artifacts'  (faulty screen output), seems to be CSS-related! 

Those 'faulty'-renderings are visible on different platforms, PC-x64, PX-x86 and Arm architectures (other architectures/platforms have not been tested).

I've included some stripped html/css code that can show the faulty behavior.

Enclosed is a zip file that allows to simulate the behavior (Webcontent.zip).

When e.g. row '001:' is clicked, the BMS_ui_adm() event handler makes <fieldset class="dialog" id="AdmValue"> visible. That is when an 'orange shape' appears on the lower right half of the display. 
(Remember this is a cut-and-paste snippet of production code all put in one file to simulate the issue).


NOTE: this problem seems to happen whenever two adjacent sides for the <fieldset> element have EXACTLY the same color defined.

For instance, the following code in the test case (line 729 in CSS file):

  fieldset {
      border-width: 3px;
      border-style: solid;
      border-color: #5e5e5e #ffbc00 #ffbc00 #5e5e5e;
  }

...it's exposing the bug because the right&bottom sides of border have exactly the same colour (orange). In the same way, the fact that top&left have the same exact colour (gray) is also causing a similar problem.

You can test this theory by quickly workaround the problem you're seeing by slightly modifying those colours, so that adjacent sides don't have exactly the same colour. For instance, this hides the bug for me:

  fieldset {
      border-width: 3px;
      border-style: solid;
      border-color: #5e5e5f #ffbc01 #ffbc00 #5e5e5e;
  }

But still, this looks like a bug (works fine in Firefox 41 and Chrome 45), so I'd say reporting it in bugzilla is the way to go.

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