a close event is not fired for a tooltip

[flamant]

Hi,
I implemented a tooltip, and I want to destroy it when I close it. Unfortunately when I close the toolTip, the close event isn't fired :

    var toolTip = new Ext.ToolTip({
        title: '      '+'<spring:message code="application.auditTrail"/>',
        id: 'quickTip_'+field.fieldId,
        target: field.getId(),
        anchor: 'left',
        iconCls: 'auditTrail',
        html: null,
        autoHide: false,
        closable: true,
        height: 200,
        width: 500,
        items: {
            xtype: 'form',
            layout: 'fit',
            height: 200,
            width: 500,
            items: grid
        },
        layout: 'fit',
        listeners : {
            close : function(panel) {
                console.log('it works');
                panel.destroy();
            }
        }

Thank you in advance for your answers