Cover screen with window in cocoa

I am writing a Mac application, in Cocoa, that needs the ability to 'lock down' the computer. Basically, I am writing a small agent that will sit in the background and when prompted, throw up a window that covers the entire screen, including the status bar, and shows a message (something like "give me back my computer, thief!").

The window has two requirements: it can't be moved and it can't be closed, minimized or otherwise disabled - just a big blob sitting on the screen, making sure the thief can't us开发者_StackOverflow中文版e the computer. I have all the agent stuff lined up, but I need help coding this window. Does anyone have any ideas?

Thanks,

Chris

P.S - In my dream world, this window would show up even at the login screen. The agent will be running by then, but I am not sure if OS X will allow it...

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What you're asking for is basically to turn the user's computer into a not-very-functional kiosk. See also this technote on the same subject.

For display, alternatives to the full-screen view mode described in the Kiosk Mode document include:

• Capture all the displays and draw directly to them using Quartz Display Services.
• Set your window's frame to the frame of its screen and set its window level really high. You'll need to create one such window per screen.