GERARD LARDNER wrote:
Making Custom Controls Persistent.
This page seems to have disappeared. I could find it only on the Internet Archive, at http://web.archive.org/web/20090509190604/http://www.imakenews.com/ptcexpress/e_article001061554.cfm
Or here:
http://download.ptc.com/products/mathcad/files/april-08/custom-controls13.xmcdz
Use right click and then "save as"