How to: Provide Automation for Windows
You can provide automation for document and tool windows. Providing automation is advisable whenever you want to make automation objects available on a window, and the environment does not already provide a ready-made automation object, as it does with a task list.
Automation for Tool Windows
The environment provides automation on a tool window by returning a standard Window object as explained in the following procedure:
To provide automation for tool windows
Call the GetProperty method via the environment with VSFPROPID_ExtWindowObject as VSFPROPID parameter to get the Window object.
When a caller requests a VSPackage-specific automation object for your tool window through Object(), the environment calls QueryInterface for IExtensibleObject, IVsExtensibleObject, or the IDispatch interfaces. Both IExtensibleObject and IVsExtensibleObject provide a GetAutomationObject method.
When the environment then calls the GetAutomationObject method passing NULL, respond by passing back your VSPackage-specific object.
If calling QueryInterface for IExtensibleObject and IVsExtensibleObject fails, then the environment calls QueryInterface for IDispatch.
Automation for Document Windows
A standard Document object is also available from the environment, although an editor can have its own implementation of the T:EnvDTE.Document object by implementing IExtensibleObject interface and responding to GetAutomationObject.
In addition, an editor can provide a VSPackage-specific automation object, retrieved through the Object(String) method, by implementing the IVsExtensibleObject or IExtensibleObject interfaces. The Basic Edit sample contributes an RTF document-specific automation object.