rem: new Effect.MoveBy(element, -top_offset, -left_offset, {duration:dur}); 
add: element._revert = new Effect.MoveBy(element, -top_offset, -left_offset, {duration:dur}); 
context:       reverteffect: function(element, top_offset, left_offset) {        var dur = Math.sqrt(Math.abs(top_offset^2)+Math.abs(left_offset^2))*0.02;        new Effect.MoveBy(element, -top_offset, -left_offset, {duration:dur});      },
meta: 7994	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/7994/08ca862091194b85b405f2c8d24c8c00908204ef/dragdrop.js/buggy/src/dragdrop.js