RadControls for ASP.NET AJAX 
SYMPTOMS
The text in the TextBox doesn't scroll when you move the cursor
using the arrow keys.
CAUSE
The displayed text is in the TextBox, but the cursor is in the
file input. The cursor position for the visible part of the text in the file input and the
TextBox cannot be controlled using javascript.
RESOLUTION
Disable text editing in the file input by setting
ReadOnlyFileInputs
property to true, or Set EnableFileInputSkinning
property to false.