Enters a DBNull.Value into the column.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
This method is called when the user presses ALT+0 to allow a column to enter the appropriate null value. For example, when called on a DataGridTextBoxColumn, the appropriate NullText value is inserted into the column.
The has no default behavior. When inheriting from DataGridColumnStyle, override the method to enter null in a column.