Miscellaneous fixes

I put them all in a single pull request since they involve very small, uncontroversial changes.

* ~~Remove duplicated allocation of JMenuBar~~
* Avoid boxing/unboxing when parsing primitive
* Avoid inefficient use of new String(String)
* Use valueOf factory method instead of constructor
* Add missing static modifier to inner classes
* Remove unused PresentMode.device instance variable
* Add volatile modifier to ColorSelector.selector