- Made the hidden input type to have 0 height for meta boxes.
- Added: the *addSubMenuItems()* and *addSubMenuItem()* methods that enables to add not only sub menu pages but also external links.
* Added: the *addSubMenuItems()* and *addSubMenuItem()* methods that enables to add not only sub menu pages but also external links.
- Changed to use the addSubMenuItems() method instead of addSubMenuPages().
- Added an external link to the sidebar menu.