cocoa: changed in window visiblity management

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@43491 4005530d-fff6-0310-9dd1-cebe43e6787f
cocoa: fix typo

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@43492 4005530d-fff6-0310-9dd1-cebe43e6787f