WIP: Input focus handling

[gamingrobot]

When a child window is spawned by open_parented the KEYUP/KEYDOWN events are still sent to the parent. This makes it so the child becomes focused so key events can go to its wnd_proc function.

[robbert-vdh]

I'd say the correct solution would be to add callbacks to baseview to allow the application to grab and release input focus as needed. That sounds like a much better idea than grabbing input focus on mouse down and then never returning it again.