Is it possible to add more than one viewport in an application. Since we can add other containers more than one time and viewport is also a container.
I think of the Viewport as representing all of the possible viewing space of the web browser window. It is a special Container that re-sizes as the web browser re-sizes. In a full screen ExtJS application, all the other containers should all be nested under the single Viewport so that they can re-size themselves relative to the browser window as well. For this reason there is no concept of multiple ExtJS Viewports.
If, instead of a full screen ExtJS application, you wish to have multiple ExtJS widget applications embedded in div tags of some static html page then Viewport should probably not be used. Container or Panel objects can be the top level parent.