In blue, code needed to add support to the grid reconfigure event

Code:
        init: function(grid) {
            grid.on('afterrender',
                function(){
                    Ext.Array.forEach(grid.query('headercontainer'), this.initColumn, this);
  grid.on('reconfigure', this.handleGridReconfigure, this);
                },
                this);
        },

        handleGridReconfigure: function(grid){
            Ext.Array.forEach(grid.query('headercontainer'), this.updateColumnTextIfNeeded, this);
        },