If you choose a file with the file upload component, then do any kind of
postback to the page, the chosen file is gone and the textfield is empty.

Steps to reproduce:

1. Add a textfield and make it required
2. add a file upload component
3. add a message group
4. add a button.
5. run the web app.
6. choose a file with the browse button for the file upload
7. now push the button you added.
8. a postback will happen because of a validation error and the file updload
component textfield is empty.

I've tried everything including binding the file upload component to an
"UpLoadedFile" but the choosen file value ALWAYS goes away.