I changed the C68 libc_a (not libcurses_a !) from version 4.22f to 4.22i and the wild linefeed problem magically disappeared. Unfortunately most file downloads are no longer available Dave Walker's Website, so I don't know which details had changed.
Has someone got a changelog?
But with libc_a 4.22i the keyboard input stopped to work correctly. Looks like I have the choice between scrambled screen output (f) or no cursor keys (i) :-((
DW's website says 4.22i fixes a problem reported by Thierry concerning scanf(). Thierry, if you're here, could you make a guess if that fix could have broken something?
All the best Peter