MFC C++ Derived CFileDialog can't tell when filename editbox is edited

Question

I have a custom derived CFileDialog. I can detect when the list control is updated, and the user clicks a file, but I can't find any way to tell when the user just types in the filename. This would be ideal, as based on what file they chooses, it adjusts another custom textbox. So without being able to tell when the user just types manually, to update that, it's not as useful unfortunately.