[Webkit-unassigned] [Bug 67203] New: Absolutely positioned div with canvas child does not move with parent div.

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=67203

           Summary: Absolutely positioned div with canvas child does not
                    move with parent div.
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Macintosh Intel
               URL: http://www.lucidchart.com/bugreports/webkitBug.html
        OS/Version: Mac OS X 10.7
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P2
         Component: New Bugs
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: madsenat at gmail.com


The above URL shows a simple process block we use in our online diagramming application. After a few seconds I highlight the divs, remove some extra DOM elements that are not needed for the demo, and add the event handlers for the demo. The final DOM structure is as follows:

<p /> - hidden
<p />
<div>
    <div>
        <canvas /> (shape canvas)
        <div>
            <canvas /> (text canvas)
        </div>
    </div>
</div>

If you drag around the element you will see that the canvas the text is rendered on (in blue) stays in place while the div parent of the canvas (green) stays where it should be. You can press the 'x' key to toggle the visibility of the text canvas (css display set to 'none' and 'block' appropriately) and when you show it again it will be in the right place.

Another interesting note is that if you reverse the order of the outer canvas (where the block shape is rendered) and it's sibling div (the parent of the text canvas) then they stay together just fine. You can use the 'y' key to see this in action.

We see the same issues on the beta channel of Chrome and it appears to be a GPU acceleration thing as we can locate a GPU acceleration related process and kill it and everything snaps back to the right place.

To see this issue in our production environment you can visit lucidchart.com/demo and drag a block from the left hand column onto the page then drag it around.

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