Windows NT 4.0 User Manager lets an administrator select multiple users and groups at the same time in the User Properties dialog box and examine or change their security properties. Recently, I discovered that when multiple accounts are selected, the properties can be in one of three states: a selected state, an unselected state, or a selected and dimmed state. Can you explain what these three states mean?

Figure 1 shows the User Properties dialog box. Four user accounts are selected, and all three states are represented. The User Must Change Password at Next Logon property and the Accounts Disabled property are unselected, the Users Cannot Change Password property is unselected and shaded, and the Passwords Never Expire property is selected. A selected check box means that the property is set for all the selected accounts, a selected and shaded check box means that the property is set for some but not all selected accounts, and an unselected check box means that the property is set for none of the selected accounts.