Making an accordion element refresh its layout when expanded

[CCExp]

Does anyone know how to call doLayout() on an item when it is expanded? I have an application where there's an accordion element containing several formpanels. These formpanels have composite fields that don't render on the non-expanded formpanels, but I can make them render by using the form's doLayout() function. I have tried adding this property to the form using the onExpand property:

Ext.form.CalcFormPanel = Ext.extend(Ext.form.FormPanel, {
    labelWidth: 75,
    bodyStyle:'padding:5px 5px 0',
    border:false,
    onExpand: function() {
        this.doLayout();
    },
    width: 280,
    defaults: {width: 80},
    forceLayout: true,
    defaultType: 'textfield'
});

But this causes my form not to work and throws JS error messages. Does anyone know how I can cause the doLayout() function to fire whenever a given form in the accordion is expanded? Thanks for any help.

[jay@moduscreate.com]

You can't add arbitrary members to a class and expect the class to call it.

Ext.form.CalcFormPanel = Ext.extend(Ext.form.FormPanel, {
    labelWidth: 75,
    bodyStyle:'padding:5px 5px 0',
    border:false,
    initComponent: function() {
        Ext.form.CalcFormPanel.superclass.initComponent.call(this);
        this.on('expand', this.doLayout, this);
    },
    width: 280,
    defaults: {width: 80},
    forceLayout: true,
    defaultType: 'textfield'
});