Forcing the client area of the window to be the size it should be.

* Hopefully an end to the endless story.
* After packing, force the size we need (actually seems only be
  needed on Linux but  hey, on the safe side ;-) )
* Removed pending tests
* Also made the DSL app only relay the call to the gui if the gui
  has already started
refactored app a bit (scroll bar and code moved to private section)
Opps add Shoes.display for redraws, weirdly merge gone wrong
simple-app-dimensions.rb has never been a real sample.
Merge pull request #368 from PragTob/rebased_endless_story

Endless Story: fixing platform app width issues