It is suitable for a page with one extension control (for example, a Map control or a Chart control). When you create an extension page, a page with an extension control is created.
Extension Page in Web IDE Mobile Development Kit Editor¶
For the main area of the extension page, there is only one extension control. You cannot remove the existing control or add additional controls.
For the footer area or header area of the extension page, you can add
Action Bar Item and