If the grid is created inside a hiden parent (parent hidden before grid created, like a jquery UI dialog), errors occure unless the following code is added:
getTop: function(ri, actual) {
var top = this.topArr ? this.topArr[ri] : 0,
....
getLeft: function(_ci, actual) {
if(typeof(this.leftArr)==="undefined") return 0;
....
calcTopBottom: function(left) {
if(typeof(this.dims)==="undefined") return 0;
...
