I'm not sure whether others have noticed this as well or not. In couple of my cases, I noticed that when a column is hidden in the stored state and state is restored on a rendered grid, grid headers remain visible while content is hidden. I propose the following fix:

Code:
Ext.grid.GridPanel.override({
    applyState : function(state){
        var cm = this.colModel;
        var cs = state.columns;
        if(cs){
            for(var i = 0, len = cs.length; i < len; i++){
                var s = cs[i];
                var c = cm.getColumnById(s.id);
                if(c){
                    c.width = s.width;
                    var oldIndex = cm.getIndexById(s.id);
                    cm.setHidden(oldIndex, s.hidden);
                    if(oldIndex != i){
                        cm.moveColumn(oldIndex, i);
                    }
                }
            }
        }
        if(state.sort){
            this.store[this.store.remoteSort ? 'setDefaultSort' : 'sort'](state.sort.field, state.sort.direction);
        }
    }
});