rubymotion/teacup — pull request #52 by colinta (2012-10-28 00:14:57+00:00)
Title: calculate relative widths

based on [this discussion](https://github.com/rubymotion/teacup/issues/49), I implemented a `Teacup.calculate` method that can accept a number (which it returns untouched), a percent (e.g. `'100%'`) or a `Proc`, which is handed the superview as the only argument, and called using `instance_exec`, so `self` is the view being styled.