Hi Rod,
Sorry for the inconvenience caused to you. The issue you have mentioned is a know one for which a feature request has been made. Currently it is not possible to change the width/height size alone and the reason for it is as follows:
Diagram.Windows allows us to change width or height. In ASP.NET we use rectangle image for each node, that's why we can't find only node area. User can't change aspect ratio.
Note: Diagram.Web resizing behavior is like group node resizing behavior in Diagram.Windows. Which you can notice in the attached zip file containing the images.
Regards,
Dinesh
nodeWeb_730e9338.zip