970823 - combobox needed in datagridview

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WinForms

DataGridView

In a WinForm application, I've a DataGridView control. I don't add any column to it. I just set its DataSource to a list. The list is of type Field which is a class I wrote. It contains of three members, Name of type string, Type of type string and Len of type int. This causes no problem and the DataGridView fills with the proper content. But now I need the second column (Type) to be shown as a non-editable Combobox instead of a simple string, so that the user may just select from the predefined objects.
How can it be possible?

What I have tried:

I thought the type of the column should be a function of the type of the member. So I changed Type from string to an enumeration. But this didn't help.