the special text editing 'accumulating' was unfinished for too long.
Now it's gone with it's warnings.

textedit.c:148:19: warning: unused variable 'change' [-Wunused-variable]
  TextEditChange *change;
                  ^
textedit.c:370:1: warning: unused function 'text_edit_create_change' [-Wunused-function]
text_edit_create_change(Text *text)
^
textedit.c:394:1: warning: unused function 'text_edit_update' [-Wunused-function]
text_edit_update(TextEditChange *change)
^