Logon messages

Hello!

When you logon to Windows NT, does the system send any message to the top-level
window of an application which is already running as a service?

Thanks a lot...

-- Liu

[Krishnaa]

When a User logs in default interactive desktop is created and made visible , now shell is started in this desktop , and any application executes now onwords inherits the desktop.

Message can be sent to the window which is on same desktop , or having interactivity with that desktop.