Starting with Prime 6, the watermark indicating that "Prime Express" was active ("Created with PTC Mathcad Express....") moved from the page footer to a watermark that goes diagonal across the entire page. This huge banner is very distracting and makes the "Express" version way less usable. Per discussion with Mathcad technical support this was done at the request of a customer so that when using Mathcad it was obvious "Express" was being used and some calculations may not be updating. I think it is quite clear with the watermark in the page footer plus the "PTC Mathcad Express" below the menu bar (and calculations not supported in "Express" will indicate an error). Please move the watermark back to the footer (like Prime 5) or provide the functionality to select where the "Express" watermark is displayed.
