{
xtype      : 'compositefield'
,hideLabel  : true
,labelWidth : 100
,items         : [
{
    xtype  : 'displayfield'
    ,width : 160
    ,value : 'field 1'

},
{
    xtype   : 'checkbox',
    name    :'field1name',
    id    :'field1id',
    checked : true
},
{
    xtype  :  'displayfield'
    ,width : 20
    ,value:'Ft '
},
{
    xtype: 'numberfield',
    width:50,
    allowNegative:false,
    value:50,
    name:'numberfield'

}

{
 xtype      : 'compositefield'
 ,hideLabel  : true
 ,labelWidth : 100
 ,monitorValid: true
 ,items         : [
 [...]
 {
   xtype: 'numberfield',
   width:50,
   allowNegative:false,
   value:50,
   name:'numberfield',
   validator: function(val) {
     if (!Ext.isEmpty(val)) {
        return true;
     } else {
         return "Value cannot be empty";
     }
   }
}