/**
 * @class Ext.form.CheckboxGroup
 * @extends Ext.form.Field
 * 
A grouping container for {@link Ext.form.Checkbox} controls.
 * 
Sample usage:
 * 

var myCheckboxGroup = new Ext.form.CheckboxGroup({
    id:'myGroup',
    xtype: 'checkboxgroup',
    fieldLabel: 'Single Column',
    itemCls: 'x-check-group-alt',
    // Put all controls in a single column with width 100%
    columns: 1,
    items: [
        {boxLabel: 'Item 1', name: 'cb-col-1'},
        {boxLabel: 'Item 2', name: 'cb-col-2', checked: true},
        {boxLabel: 'Item 3', name: 'cb-col-3'}
    ]
});
 * 
 * @constructor
 * Creates a new CheckboxGroup
 * @param {Object} config Configuration options
 * @xtype checkboxgroup
 */
Ext.form.CheckboxGroup = Ext.extend(Ext.form.Field, {
    
/**
     * @cfg {Array} items An Array of {@link Ext.form.Checkbox Checkbox}es or Checkbox config objects
     * to arrange in the group.
     */
    
/**
     * @cfg {String/Number/Array} columns Specifies the number of columns to use when displaying grouped
     * checkbox/radio controls using automatic layout.  This config can take several types of values:
     * 
'auto' : 
The controls will be rendered one per column on one row and the width
     * of each column will be evenly distributed based on the width of the overall field container. This is the default.
     * 
Number : 
If you specific a number (e.g., 3) that number of columns will be 
     * created and the contained controls will be automatically distributed based on the value of {@link #vertical}.
     * 
Array : Object
You can also specify an array of column widths, mixing integer
     * (fixed width) and float (percentage width) values as needed (e.g., [100, .25, .75]). Any integer values will
     * be rendered first, then any float values will be calculated as a percentage of the remaining space. Float
     * values do not have to add up to 1 (100%) although if you want the controls to take up the entire field
     * container you should do so.
     */
    columns : 'auto',
    
/**
     * @cfg {Boolean} vertical True to distribute contained controls across columns, completely filling each column 
     * top to bottom before starting on the next column.  The number of controls in each column will be automatically
     * calculated to keep columns as even as possible.  The default value is false, so that controls will be added
     * to columns one at a time, completely filling each row left to right before starting on the next row.
     */
    vertical : false,
    
/**
     * @cfg {Boolean} allowBlank False to validate that at least one item in the group is checked (defaults to true).
     * If no items are selected at validation time, {@link @blankText} will be used as the error text.
     */
    allowBlank : true,
    
/**
     * @cfg {String} blankText Error text to display if the {@link #allowBlank} validation fails (defaults to "You must 
     * select at least one item in this group")
     */
    blankText : "You must select at least one item in this group",
    
    // private
    defaultType : 'checkbox',
    
    // private
    groupCls : 'x-form-check-group',
    
    // private
    initComponent: function(){
        this.addEvents(
            
/**
             * @event change
             * Fires when the state of a child checkbox changes.
             * @param {Ext.form.CheckboxGroup} this
             * @param {Array} checked An array containing the checked boxes.
             */
            'change'
        );   
        Ext.form.CheckboxGroup.superclass.initComponent.call(this);
    },
    
    // private
    onRender : function(ct, position){
        if(!this.el){
            var panelCfg = {
                cls: this.groupCls,
                layout: 'column',
                border: false,
                renderTo: ct
            };
            var colCfg = {
                defaultType: this.defaultType,
                layout: 'form',
                border: false,
                defaults: {
                    hideLabel: true,
                    anchor: '100%'
                }
            };
            
            if(this.items[0].items){
                
                // The container has standard ColumnLayout configs, so pass them in directly
                
                Ext.apply(panelCfg, {
                    layoutConfig: {columns: this.items.length},
                    defaults: this.defaults,
                    items: this.items
                });
                for(var i=0, len=this.items.length; i0 && i%rows==0){
                            ri++;
                        }
                        if(this.items[i].fieldLabel){
                            this.items[i].hideLabel = false;
                        }
                        cols[ri].items.push(this.items[i]);
                    };
                }else{
                    for(var i=0, len=this.items.length; i