By default when you edit a column AdapTable will show whichever cell editor you stipulated for that column when you set up ag-Grid.
However, in the User Interface section of Predefined Config you can stipulate that a column will automatically display a Dropdown (select) when being edited.
Simply list the columns that should display a Dropdown in the EditLookUpItems property and Adaptable will do the rest. If you wish, you may also provide a list of values to display in the dropdown.
If no values are provided then the Dropdown will be populated first with Server Lookups (if set), then by Permitted Values (if set) and lastly (and the default) by getting distinct values for that Column dynamically.
This example shows 3 column dropdowns: Cust Ref (which is given a list of 15 values to show), Contact (which is populated via Permitted Values) and Employee (which gets distinct column values dynamically).