Returns or sets the name of the procedure that’s run whenever you activate a window. Read/write String.
Remarks
The procedure specified by this property isn’t run when other procedures switch to the window or when a command to switch to a window is received through a DDE channel. Instead, the procedure responds to the user's actions, such as clicking a window with the mouse, clicking Go To on the Edit menu, and so on.
If a worksheet or macro sheet has an Auto_Activate or Auto_Deactivate macro defined for it, those macros will be run after the procedure specified by the OnWindow property.
Example
This example causes the WindowActivate procedure to be run whenever window one is activated.
ThisWorkbook.Windows(1).OnWindow = "WindowActivate"