chromium/third_party/blink/manual_tests/autoscroll-over-scrollbar.html

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    <body> 
        <h1><a href="https://bugs.webkit.org/show_bug.cgi?id=40403">Bug 40403</a></h1>
        <p>Click down somewhere in this text, then move the pointer over the scrollbar at the bottom of the window, stop there, holding the mouse button down.</p>
        <div style="height:3000px; width:3000px;"></div>
        <p>If the bug occurs, then this text won't be selected until you move the mouse slightly. If the bug does not occur, this text should be selected.</p>
    </body>
</html>