[jussij]

A computer windowing system does not model real windows, it models pieces of paper, spread across a desk.

On a desk cluttered with papers, you can see bits of some papers and others papers are hidden by other papers that are on top.

There is no way you should be able to patent such an obvious real world, real life experience, just because you were the first to take that real world experience and replicate it on a computer screen.

All you have done is modeled a real work experience.