Made some cahnges so that gleam will be more tolerant of different resolutions.

There's some oddness with the ScrollBar and the text doesn't scale, but everything
works rather swimmingly in other resolutions now.

Also, some of the dialog classes may need to be updated.  I didn't test everythin.
Added class ScreenConfig, which stores information pertaining to the screen and how it maps to
the underlying window.  This will be used to divorce screen coordinates from window coordinates.