This screen is accessed from the back-end Joomla! administrator panel. It is used to create a new or edit an existing module
This section contains all the menu items configured in your Joomla! website. To apply the current style to a menu item's corresponding web page, check the box next to the menu item. You can press the Toggle Selection button to invert the menu item selections.
Note: If a checkbox is grayed out and cannot be checked then it could be because the menu item is in use by another user. You can see if this is the case by going to the menu manager screen for the menu concerned. If there is a padlock symbol next to the menu item then it is currently in use by another user.
At the top right you will see the toolbar:
The functions are: