只要是component都可以用plugins
plugin必須含有init方法

使用插件：
var checkColumn = new Ext.grid.CheckColumn({//生成一個
       header: "Indoor?",
       dataIndex: 'indoor',
       width: 55
    });
new Ext.grid.EditorGridPanel({
        store: store,
        cm: cm,
        renderTo: 'editor-grid',
        width:600,
        height:300,
        autoExpandColumn:'common',
        title:'Edit Plants?',
        frame:true,
        plugins:checkColumn,//**********列舉要使用的插件
        clicksToEdit:1});

 var cm = new Ext.grid.ColumnModel([{
           id:'common',
           header: "Common Name",
           dataIndex: 'common',
           width: 220,
           editor: new fm.TextField({
               allowBlank: false
           })
        },
        checkColumn//使用插件
    ]);


自定義插件（即自定義一個包含init()方法 的類），這里是定義一個和CheckBox類似的東西，有很多處我沒看懂
Ext.grid.CheckColumn = function(config){
    Ext.apply(this, config);
    if(!this.id){
        this.id = Ext.id();
    }
    this.renderer = this.renderer.createDelegate(this);
};

Ext.grid.CheckColumn.prototype ={
    init : function(grid){
        this.grid = grid;
        this.grid.on('render', function(){
            var view = this.grid.getView();
            view.mainBody.on('mousedown', this.onMouseDown, this);
        }, this);
    },

    onMouseDown : function(e, t){
        if(t.className && t.className.indexOf('x-grid3-cc-'+this.id) != -1){
            e.stopEvent();
            var index = this.grid.getView().findRowIndex(t);
            var record = this.grid.store.getAt(index);
            record.set(this.dataIndex, !record.data[this.dataIndex]);
        }
    },

    renderer : function(v, p, record){
        p.css += ' x-grid3-check-col-td';
        return '<div class="x-grid3-check-col'+(v?'-on':'')+' x-grid3-cc-'+this.id+'"> </div>';
    }