In this direction, I'm trying to call a function in the shell32.dll lib that apparently should let you minimize an app to the system tray, but I'm not having much luck... I guess I don't really understand what am I exactly doing. This is what I found in the MSDN<http://msdn.microsoft.com/en-us/library/bb762159%28VS.85%29.aspx> : BOOL Shell_NotifyIcon( _In_ DWORD dwMessage, _In_ PNOTIFYICONDATA lpdata ); So, I tried to translate this into Pharo as: MyClass >> minimizeToTray: dwMessage data: lpData <apicall: bool 'Shell_NotifyIcon' (dword PNOTIFYICONDATA) module: 'shell32.dll'> But it won't let me save the method, reporting it's expecting an argument before PNOTIFYICONDATA. I realize PNOTIFYICONDATA is not a primitive type, but I just don't know how to handle it... :(