When a dimension on a drawing in Solidworks looses it's reference it becomes a dangling dimension and changes color.  If I click on the dimension the pick point is red.  If I pick on the red end of the dimension I can grab it and move it to it's new reference but it never sticks.  No matter what I do I can never seem to re-associate the dangling dimension.  I also use NX and it is so easy to do this.  What am I missing with Solidworks?  What do I need to do to un-dangle these dimensions?