ExtJS - EditorGridPanel: error when cell is selected

I'm getting an error when selecting cells in my EditorGridPanel. Here's a snippet of my code:

var bannerGrid = new Ext.grid.EditorGridPanel({
    store: bannerStore,             
    cm:开发者_开发技巧 new Ext.grid.ColumnModel({
        defaults: {
            sortable: true,
            menuDisabled: true
        },
        columns:
            { 
                header: '<img src="img/oo-icon.png" />&nbsp;<img src="img/network-icon.png" />', 
                width: 52, 
                dataIndex: 'inventory', 
                align: 'center',
                renderer: inventoryIcon,
            }, { 
                header: "Name", 
                dataIndex: 'bannerName',
                editor: new Ext.form.TextField({ allowBlank: false }),
                width: 300
            }, { 
                header: "Advertiser", 
                dataIndex: 'advertiser',
                editor: advertisersDropdownGrid,
            }, { 
                header: "Art Type", 
                dataIndex: 'artType',
                editor: artTypeDropdownGrid,
            }, {
        ......

Each of the 'editors' are dropdowns that are defined prior to the grid. The weird thing is that the editor that contains the TextField does not throw the same error.

The error I'm getting when selecting a cell is this:

c.getItemCt() is undefined
[Break On This Error] c.getItemCt().removeClass('x-hide-' + c.hideMode); 

Again, this only happens on the ComboBox editors!

From further inspection the error is coming from this part of ext itself:

onFieldShow: function(c){
c.getItemCt().removeClass('x-hide-' + c.hideMode);
    if (c.isComposite) {
        c.doLayout();
    }
}, 

Which seems to be part of the FormLayout section.

Any ideas? I've tried defining the Combo's inline and that did not fix it.

Thanks!

EDIT: Here's how I define my Combo's using classes.

I define my ComboBoxJSON class: (I've blanked out namespaces just for privacy sake)

***.***.***.ComboBoxJSON = Ext.extend(Ext.form.ComboBox, {

    url: '',
    root: '',
    valueField: 'id',
    displayField: 'name',
    width: 200,
    id: '',
    fields: [
        { name: 'id', type: 'int'}, 
        { name: 'name', type: 'string' }
    ],


    initComponent: function () {

        var comboStore = new Ext.data.JsonStore({
               id: 'JsonStore',
               idProperty: 'id',
               autoLoad: true,
               idProperty: 'id',
               root: this.root,
               fields: this.fields,
               proxy: new Ext.data.ScriptTagProxy({
                   api: {
                       read: this.url,
                   }
               })
           });  

        var config = {
            store: comboStore,
            displayField: this.displayField,
            valueField: this.valueField,
            mode: 'local',
            minChars: 1,
            triggerAction: 'all',
            typeAhead: true,
            lazyRender: true,
            value: this.value,
            width: this.width,
            id: this.id
        }

        Ext.apply(this, config);

        ***.***.***.ComboBoxJSON.superclass.initComponent(this);

    }
});

Ext.reg("ibwComboJson", ***.***.***.ComboBoxJSON);

I then define my combos before init on the grid, like so: (I've blocked out the URL, but it does return valid JSON)

var advertisersDropdownGrid = new ***.***.***.ComboBoxJSON({
    url: '***',
    root: 'advertiserList',
    id: 'advertisersDropdownGrid'           
});

---

Found the answer to this awhile back, but the solution is pretty absurdly simple.

***.***.***.ComboBoxJSON.superclass.initComponent.call(this);

Forgot the .call portion. :)