Merge pull request #57 in ZP/z-push from bugfix/ZP-704-z-push-top-screen-size-calculation-fails-under-OS-X to develop

* commit '27454aad':
  ZP-704 Fixed white space.
  ZP-704 z-push-top screen-size calculation fails under OS X. Released under the Affero GNU General Public License (AGPL) version 3.

(cherry picked from commit ba460f57)