Returns an object representing the topmost Microsoft Outlook window on the desktop, either an Explorer or an Inspector object. If no Outlook explorer or inspector is open, returns Nothing.
expression.ActiveWindow
expression Required. An expression that returns an Application object.
Example
This Microsoft Visual Basic/Visual Basic for Applications (VBA) example minimizes the topmost Outlook window if it is an inspector window.
Sub MinimizeActiveWindow()
Dim myOlApp As New Outlook.Application
If TypeName(myOlApp.ActiveWindow) = "Inspector" Then
myOlApp.ActiveWindow.WindowState = olMinimized
End If
End Sub