There is a small bug in this program. The tray icon does not disappear immediately when the program terminates. Instead, it remains in the system tray until you point the mouse cursor at it, when it disappears. This is a bug in Win32::GUI - when you close your program, you should explicitly remove any system tray icons you still have displayed. Win32::GUI does not (yet) have a way of removing a tray icon. Hopefully, this will be fixed in a later version.