Clients can retrieve the object's default action by inspecting an object's DefaultAction property. A client can use automation (if supported) instead of DoDefaultAction to perform an object's default action. However, DoDefaultAction provides an easy way to perform an object's most commonly used action.
Notes to Inheritors
The default action performed by system-provided user interface elements depends on the keyboard state. That is, if a modifier key such as SHIFT, ALT, or CTRL is down (either by a user action or programmatically) when DoDefaultAction is called, the default action might not be the same as when those keys are not down. Not all objects have a default action.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)