hi,
Set the property of textbox http://msdn.microsoft.com/en-us/library/system.windows.controls.primitives.textboxbase.acceptsreturn%28VS.85%29.aspx to true like this within msflexgrid.
<TextBox AcceptsReturn="True">Test</TextBox>
This http://msdn.microsoft.com/en-us/library/system.windows.controls.primitives.textboxbase.acceptsreturn%28VS.85%29.aspx property inherits form
TextBoxBase, so you can create your DataTemplate as a TextBox, then you can change the type of your Enter Key.
Thanks,