I have a window which is supposed to act like a Windows Vista(+) gadget; its supposed to stay on the desktop, not to appear on taskbar and the alt+tab menu, but most importantly, not to get minimized.

Here is its header:

As its style is set to None, it has no control buttons (minimize, close, etc...) but it still can be minimized using the "Show Desktop" feature and the Winkey+D combination.

How can I prevent that from happening?

Thanks!