I found a little mistacle in the layout fonction, that make my code don't work.

layout : function(){

......
var c = g.getGridEl(), cm = this.cm,
expandCol = g.autoExpandColumn,
gv = this;
....

correction :

var c = g.getGridEl();
var cm = this.cm;
var expandCol = g.autoExpandColumn;
var gv = this;


Now it's works perfectly .. thanks