The `system track' is the column on the right of this picture: <http://www.oberon.ethz.ch/native/snaps/tile.jpg> (there are more of them, of pictures, at: <http://www.oberon.ethz.ch/native/WebScreen.html>) This column can grow/shrink, can be edited (like a page of an agenda), .. et cetera; every "box" in the column might correspond to a submenu entry of Blackbox's menu-file. There are also the acme, sam, wily, ... family of editors (notice that I am an Emacs addicted myself) that should work with the same principle: I cannot find images on the web.
