The test case is here: http://code.google.com/apis/maps/documentation/examples/marker-simple.html
Just try to move the markers around and you will notice a black rectangle on them. It seems to be something related to the shadow of the popup window.
Tested with QtLauncher (with and without -graphicsbased) on Mac OS and Linux with Qt 4.7 trunk (32ecf8e8ad326ea13ec9a430c99ce540e8b4efac) and WebKit trunk (58755).
This bug was reported on the mailing list: https://lists.webkit.org/pipermail/webkit-qt/2010-April/000442.html
It's a -webkit-user-select issue. Can be reproduced by this:
data:text/html,foo<img src="http://maps.gstatic.com/intl/en_ALL/mapfiles/marker.png" style="-webkit-user-select: none">bar
Looking into it.
-webkit-user-select: none is handled by calling fillRect with an invalid Color, which we then pass on to Qt as an invalid QColor. The behavior for using an invalid QColor is unspecified.
Will talk to the graphics team if it's okey for us to pass a fully transparent brush, that will be short-circuited early on in Qt, or if that will cause us to hit slow code paths due to the transparency.
Fix landed in r58949
Revision r58949 cherry-picked into qtwebkit-2.0 with commit 51fb0ae5b1519f02b5982e77a3face2447c2ad14
*** Bug 34775 has been marked as a duplicate of this bug. ***