NotificationShow Method

public void Show(
	TrayIndicator indicator = null
)

Public Sub Show ( 
	Optional indicator As TrayIndicator = Nothing
)

member Show : 
        ?indicator : TrayIndicator 
(* Defaults:
        let _indicator = defaultArg indicator null
*)
-> unit 

On some platforms like Gtk and Windows 10 the indicator is not needed, while on the others like Windows 7 it's required. You can find out if the indicator is needed by looking at RequiresTrayIndicator property.