How to make Combobox in winforms readonly

The article ComboBox-with-read-only-behavior suggests an interesting solution:

Create both a readonly textbox and a combobox in the same place. When you want readonly mode, display the textbox, when you want it to be editable, display the combobox.

make DropDownStyle property to DropDownList instead of DropDown then handle the TextChanged event to prevent user changing text.