Say I have a class like this:
public class MyClass
{
public string Name;
public int Id;
public override string ToString()
{
return this.
There are certain conversions for which WPF will apply an implicit converter on a binding if the bound types don't match. Converting to a string can be done by calling ToString() the same way it's implicitly called in other areas of the .Net framework.
The Text binding of the TextBox is two-way by default and therefore can't use an implicit converter as a string can't be converted back to your MyClass type. The binding for the display template in the grid column is one way and can therefore use an implicit converter. I would imagine that you would get a binding error if you put the grid column into edit mode by clicking on it.