Autocomplete menu position issue when positioned to the right

$("input#test").width(100).autocomplete({ position: { my: "right top", at: "right bottom" }, source: ["This is a very long option", "This was a very long option"] });

While typing "this i" the menu position isn't being repositioned to the right. I guess this is because the menu is positioned using css "left", and when the width changes the absolute "right" changes which causes a "jump" is the menu position.