Improve the navigation bar
Fixed by following commit:
commit 31232053f5a6e6c460f5c53d8e286ba1a525df98 (HEAD -> master, origin/master, origin/HEAD) Author: Steel Wheels Project <wheel@tcn.zaq.ne.jp> Date: Sun Feb 17 07:00:19 2019 +0900 KCNavigationBar: Hide buttons when it is not enables (OSX)
Hide the buttons in the navigation bar when it is NOT used. Now, the button become inactive but not hidden.