ATL implements contained windows with CContainedWindowT. A contained window represents a window that delegates its messages to a container object instead of handling them in its own class.

With contained windows, you can either superclass an existing Windows class or subclass an existing window. To create a window that superclasses an existing Windows class, first specify the existing class name in the constructor for the CContainedWindowT object. Then call CContainedWindowT::Create. To subclass an existing window, you don't need to specify a Windows class name (pass NULL to the constructor). Simply call the CContainedWindowT::SubclassWindow method with the handle to the window being subclassed.

You typically use contained windows as data members of a container class. The container does not need to be a window; however, it must derive from CMessageMap.

A contained window can use alternate message maps to handle its messages. If you have more than one contained window, you should declare several alternate message maps, each corresponding to a separate contained window.

Following is an example of a container class with two contained windows:

[!code-cppNVC_ATL_Windowing#67]

For more information about contained windows, see the SUBEDIT sample.

Window Classes