Selection.Active Property (Word)
True if the selection in the specified window or pane is active. Read-only Boolean.
Required. A variable that represents a Selection object.
This example splits the active window into two panes and activates the selection in the first pane, if it isn't already active.
ActiveDocument.ActiveWindow.Split = True
If ActiveDocument.ActiveWindow.Panes(1).Selection _
.Active = False Then