Tooltip is not appeared if it overlays cursor position on element

Tooltip is not appeared if it overlays cursor position on element

Hello,
Tooltip is not appeared if it overlays cursor position on element. The code is below:
    $(function() {
        $('#example tbody').tooltip({
            content:  function() { return $(this).attr('title'); },
            position: { my: 'left top', at: 'left top', of: window, collision: 'fit fit' },
            show:     { delay: 400 },
            hide:     false
        });
    });

Thank you in advance,
LP