In the end we decided to use the following hack:
open: function (event, ui) {
updateTooltipPositions();
}
function updateTooltipPositions() {
$("[id^='ui-tooltip-']").css("left", mouseX-401);
$("[id^='ui-tooltip-']").css("top", mouseY+1);
}
In addition, IE was giving us some problems with manually closing tooltips. To avoid that we had to force that particular page out of quirks mode:
<cfheader name="X-UA-Compatible" value="IE=Edge"> <!--- Force browser into standards mode --->
Neither of these are optimal solutions. However, they worked for our time-sensitive situation.