Maybe, for some reason you want to know if the user have the Windows extension (Windows Plus) installed on his/her's Windows machine. Then you can use the following function:

function WindowsExtensionInstalled : boolean;

begin
  Result := SystemParametersInfo(SPI_GETWINDOWSEXTENSION, 1, nil, 0);
end;

The function returns a value of TRUE if Windows Plus is installed or FALSE, otherwise.

NOTE: This function will only work on Windows'95/98 (maybe 2000) and so it doesn't support Windows NT.

This tip is partially based on a tip sent by Emiel Hollander.
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