namespace hello;

interface
uses
    System,
    System.Runtime.InteropServices;

type
    Hello =  static class
public
    [DllImport('user32.dll')]
    method MessageBox(hwnd: Integer; text: String; caption: String; utype: Integer): Integer; external;
    class method Main(args: array of String): Integer;
end;

implementation

[STAThread] 
class method Hello.Main(args: array of String): Integer;
begin
    MessageBox( 0, 'Hello, Win32 API(Oxygene) World!', 'Hello, World!', 0 );
end;

end.