As a user, after compilation, set the intermediate state (checked gray) in checkedListBox . Since it is checkedListBox1.SetItemCheckState(i, CheckState.Indeterminate); already programmatically puts it.

    1 answer 1

    There is no such possibility. The intermediate state can only be set programmatically. From the documentation :

    It is not CheckedListBox provide a mechanism for CheckedListBox .