gistfile1.js

    Button = Y.Base.create('toolbar-button',Y.Widget,[Y.WidgetChild],{
        BOUNDING_TEMPLATE : '<li/>',
        CONTENT_TEMPLATE : '<button/>',
        _clickHandle : null,
        className : '',
        
        initializer : function(config) {
    		this.className = this.getClassName();
    	},
        
        renderUI : function(){
            var cb = this.get('contentBox');
            
            cb.set('text',this.get('label'));
        },
        
        bindUI : function(){
            var cb = this.get('contentBox');
            
            this._uiBindCallback( this.get('callback') );
            
            this.after('callbackChange', this._afterCallbackChange);
            
            cb.on('mouseenter', Y.bind(function(e){ cb.addClass(this.className + '-hover'); }, this));
            cb.on('mouseleave', Y.bind(function(e){ cb.removeClass(this.className + '-hover'); }, this));
        },
        
        syncUI : function(){
        
        },
        
        _uiBindCallback : function(callback) {
        	if(this._clickHandle) {
        		this._clickHandle.detach();
        	}

        	if(callback) {
        		this._clickHandle = this.on('click',Y.bind(callback,this));
        	}
        },
        
        _afterCallbackChange : function(e) {
       		this._bindClick(e.newVal);
        }
    },{
        ATTRS : {
            label : {
                value : null,
                validator : Y.Lang.isString
            },
            callback : {
                value: function () {},
            	validator : Y.Lang.isFunction
            }
        }
    });

gistfile2.js

YUI.add('file-manager',function(Y){

	var File,
	    NAME = 'fileManager',
	    NS = 'files'
	    ;
	
	File = function(config) {
		File.superclass.constructor.apply(this,arguments);
	};
	
	Y.extend(File, Y.Plugin.Base, {
		initializer : function() {
			this.bindUI();
		},
		
		bindUI : function() {
			var buttons = this.get('host').toolbar.get('buttons');
			
			if(buttons.save) {
				var btn = buttons.save;
				btn.set('callback',Y.bind(function(e){
					e.preventDefault();
					Y.log('UPLOAD!!');
				},btn));
			}
			
		}
	},{
		NAME : NAME,
		NS : NS,
		ATTRS : {}
	});
	
	Y.FileManager = File;
	
},'0.1',{requires:['plugin']});

YUI({
	modules: {
		'file-manager' : {
			fullpath : '/lib/cms/js/components/file-manager.js',
			requires : ['plugin']
		}
	}
}).use('file-manager',function(Y){
	CMS.plug(Y.FileManager);
	CMS.addPlugin('files');
});