hi ,all.
I wrote the following code to build a form.

Code:
 var btnCreateSmeta=function(){
        var createCpxFrm= new Ext.FormPanel({
                labelWidth: 75,
                url:'cpxmeta/save',
                frame:true,
                title:'创建复合元数据',
                bodyStyle:'padding:5px 5px 0',
                width: 350,
                height:400,
                defaults: {width: 230},
                defaultType: 'textfield',
                items:[{
                        fieldLabel:'名称',
                        name:'mname',
                        allowBlank:false
                     },
                    new Ext.form.TextArea({
                        fieldLabel:'描述',
                        name:'mdesc'
                    })
                ],
            buttons:[
                {
                    text:'保存',
                    formBind:true,
                    handler:function(){
                        createCpxFrm.getForm().submit({
                            method:'POST',
                            waiTitle:'正在保存',
                            waitMsg:'请稍后...',
                            success:function(){
                               Ext.Msg.alert('保存','成功保存'); 
                            },                        
                            failure:function(form,action){
                               Ext.Msg.alert('保存','保存失败');    
                            }
                         });
                    }
                }
            ]
            });
       //   render the containner 
        //createSmetaFrm.render('newCpxmeta');

             win=new Ext.Window({
                layout:'fit',
                width:400,
                height:200,
                closable:true,
                resizable:false,
                plain:true,
                items:[createCpxFrm]
            });
            win.show();
        };
everything was right except that the height of the field in this form always changed when the form was rendered each time
the wrong pic is :

but it should be:

thanks for any help.