in a DataGridViewComboBoxColumn of datagridview,is it possible that the value of the cell is not included in its dropdown

hi

    i know that in the combox, there are some different styles, :dropdown and dropdownlist,the difference is for one u can add values which is not included in the dropdown the other u cannot

    it seems that for DataGridViewComboBoxColumn of datagridview,all the styles is like dropdownlist.

   so it is possible or impossible to realze the similar function of "dropdown",that is to say,is it possible that the value of the cell is not included in its dropdown?

   thank u very much in advance ur kindness help

best regards

martin