Ext.onReady(function(){      var viewport = new Ext.Viewport({          layout:‘border‘, 		//html: ‘<p>第二步，一共4步</p>‘,        items:[{              region: ‘north‘,              split: true, 			title:‘north‘, 			//north, south, east, west or center)            border: true          },{              region: ‘west‘,              split: true, 			title:‘west‘,             border: true          },{              region: ‘center‘,              split: true, 			title:‘center‘,             border: true          },{              region: ‘east‘,              split: true, 			title:‘east‘,             border: true          },{              region: ‘south‘,              split: true, 			title:‘south‘,             border: true          }]      });    }); 

BorderLayout具有固定性，渲染之后就不会任意变动或改变格局。中央区域（center region）在BorderLayout设定中不可或缺。假使没有其它的区域，中央布局便会就是该布局的全部区域。The regions of a BorderLayout are fixed at render time and thereafter, no regions may be removed or added.The BorderLayout must have a center region, which will always fill the remaining space not used by the other regions in the layout.