Can't change/disable Draggable Containment after setting to parent

Can't change/disable Draggable Containment after setting to parent

MAY have actually found a bug here...
  1.     $(targetObject).draggable({
  2.         drag: function (e, ui) {
  3.             $("#rptSlideLayerEdits_ctl0" + layernum + "_tbXPos").val(theLeft);
  4.             $("#rptSlideLayerEdits_ctl0" + layernum + "_tbYPos").val(theTop);
  5.         },
  6.         stop: function (e, ui) {
  7.             saveLayer(currentLayerNumber);
  8.         },
  9.         containment: "parent"
  10.     });
So, this is the code that sets up the draggable. I have a little lock icon, when you click it, it runs this function:
  1. function disableLayerConstraint(){
  2.     $(".layerCons").attr("src", "images/mb_unlock.png");
  3.     $(targetObject).draggable({containment: null });
  4. }
I've tried null,"", and undefined to disable the constraint (there was no documentation on how to disable a constraint). Now everything works as expected, unless you drag it first. So, load the page, click the unlock, and I can drag it wherever I want. BUT, load the page, drag the object, THEN click the lock, it's still contained to parent.

Can anyone recreate this issue and confirm it's a bug?

I'm running the latest version of jQuery and UI.

Thanks!