Mockup of overlay layout changes

[Sander Dijkhuis <sander dijkhuis gmail com>]

I made a small mockup of a different overlay layout:
http://student.science.uva.nl/~sqdh/gs-mockup/
It is mostly a change of positioning, and a different way of switching between
the different overlay views.  Of couse only code can tell whether this works
better than the current design, but I thought it would be fun and maybe even
useful to create this mockup first.