This is a multi-pane, application-oriented UI layout style that supports multiple nested panels, automatic bars between regions and built-in expanding and collapsing of regions. This class is intended to be extended or created via the layout:'border' Ext.container.Container.layout config, and should generally not need to be created directly via the new keyword. Notes When using the split option, the layout will automatically insert a Ext.resizer.Splitter into the appropriate place. This will modify the underlying items collection in the container. Any Container using the Border layout must have a child item with region:'center'. The child item in the center region will always be resized to fill the remaining space not used by the other regions in the layout. Any child items with a region of west or east may be configured with either an initial width, or a Ext.layout.container.Box.flex value, or an initial percentage width string (Which is simply divided by 100 and used as a flex value). The 'center' region has a flex value of 1. Any child items with a region of north or south may be configured with either an initial height, or a Ext.layout.container.Box.flex value, or an initial percentage height string (Which is simply divided by 100 and used as a flex value). The 'center' region has a flex value of 1. There is no BorderLayout.Region class in ExtJS 4.0+