OK, for that, you want *no* Resource Group Access ACL entries with a context of 'mgr' and the setup is fairly simple.
I'm assuming the user groups are called Author and Administrator and the resource groups are called AuthorResources and AdminResources (though you can name them anything you want as long as they match the ACL entries).
You want two *Resource Group* Access ACL entries.
1. Connect the Author User Group to the AuthorResources Resource Group using a Resource Group Access ACL entry with a context of 'web' and a Policy of 'Load, List, and View' with a minimum role that the Author's will qualify for (IOW, with an equal or lower number than the authority level of the role they have in the Authors user group).
2. Do exactly the same thing for the Administrator group and the AdminResource resource group.
Flush permissions and settings.
Don't log in to the Manager.
Both resources should be hidden from all other users in the front end and logged-in Admin or Author users (logged in in the front end) should each see the one extra resource they are supposed to see.
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PLEASE, PLEASE specify the version of MODX you are using . . . PLEASE!
MODX info for everyone:
http://bobsguides.com/modx.html
[ed. note: BobRay last edited this post 14 years, 6 months ago.]