Add "All Groups" option.
Handle selection of all groups.
Handle selection of all users from All groups item.
Select all the groups.
Replace selection icons.
Replace selection icons.
Add option to toggle between user and group view.
Only use one type of menu.
Enabled or not the group submenu.
Remove group/user display menu.
Remove method displaying group menu.
Fix layout of menu items.
Replace text.
Add separator to menu.
Remove selection of user in group display.
Review selection of users when switching between views.
Make sure the group cannot be unselected if only one group.
Select "Show All users" if all users are selected

The item was not selected when re-opening the menu.
Keep the logged in user when deselection Show All Users.
Do not unselect group if not selectable.