Paul,
I'm not sure that this is what is wanted. I'm afraid that I didn't look further than the title page before recommending the documentation. I have a print copy of a very early version of the Clearwin+ Fortran Edition manual dated June 1995. By then, quite a number of things had seemed to become obsolete, often associated with 16-bit Windows, VBX controls, and DBOS (also FTN77).
At the risk of being called 'know-all', what seems to have happened is that the baby was thrown out with the bath water over the confusing terminology 'ClearWin windows'. Windows generated with WINIO@ seem to be referred to as 'Format windows', but Clearwin windows are either or both of:
(a) Windows generated with CREATE_WINDOW and managed with routines such as CLEAR_WINDOW, DESTROY_WINDOW etc.
(b) Text display areas created with %cw in a Format window
The first category of these are clearly supplanted by Format windows, but the second category are not, and they remain of use for anyone who want to use traditional Fortran formatted output (admittedly, using ESCape sequences to add bold, italic, underline, colour etc) , which one does inside the %cw text area, having attached a Fortran LUN to the %cw area with (say) OPEN_TO_WINDOW@. The earlier content of this topic related to the @ symbol, which eventually was tracked down to it being the default ESCape code, resettable by SET_WIN_ESCAPE.
Sadly, the documentation for both categories (a) and (b) above is interwoven, and despite your very clear example (and my suggestions, which I had all but forgotten), there seems to be no clear exposition of what you can or can't do with a %cw text area as distinct from a Windows Window NOT generated with WINIO@.
Even the 1995 manual needs a lot of searching in, and I can't find any better anywhere.
Eddie