Variable right-side view width

[grgcombs]

Ok, I'm not sure how much this would blow up the positioning logic, but I need some right side view controllers to be wider than the default. Default works fine for most of my tanle views, but a map view needs to be about 30-40% wider. Maybe 500-550px wide. I haven't looked much into the offset logic but I think it's expecting the default size across all stacked views on the right.