Extjs 如何禁用网格checkboxmodel的行选择，保持以前的选择完好无损

锁定网格模型后，我无法保留选择。我的代码如下

var sm = Ext.getCmp('loadFrameStateInfoTable').getSelectionModel(); // This select the rows which I want to
var stateStore = sm.store;
for (var ct in frameInfo) {
    var cd = frameInfo[ct].state_code;
    if (frameInfo[ct].st_flag == 'Y') {
        var index1 = stateStore.find('state_cd', cd);
        Ext.getCmp('loadFrameStateInfoTable').getSelectionModel().select(index1, true);
    }
}

// This lock the checkbox model
var sm = Ext.getCmp('loadFrameStateInfoTable').getSelectionModel();
if (frame_status == 'Pending' || frame_status == 'Failed' || frame_status == 'Generated') {

} else {
    Ext.getCmp('update_button').disabled = true;
    sm.setLocked(true);
}