I'm new on this list and not (yet?) user of TeXMacs. Good a year ago, for producing and typesetting handouts and literature presentation, I changed from Office to LaTeX with LyX as editor and helping cap. I'm quite good with it, though I had to learn and try much. The decident reason for this wand to LaTeX & Co. had been the possibility to make many, many helping 

sidenotes (i. e. footnotes as margin notes in the tufte doc classes), 

wellformed and comfortably, in old language's texts to present them, also for teaching goals. On the TeXMacs' website I didn't find this kind of insets mentioned, only the word "footnotes…". 

So, before I seriously consider to install and test-out TeXMacs, I would like to know, wether it has this inset-possibility - number-linked sidenotes -, too, and if yes, wether it can be done there with ease (via menu or keyboard shortcut) as well.

To make it unmistakable:

I mean numbered (little) annotations like footnotes, but put in the margin. I can't make without.