The touchwin and touchline routines throw away all optimization information about which parts of the window have been touched, by pretending that the entire window has been drawn on. This is sometimes necessary when using overlapping windows, since a change to one window affects the other window, but the records of which lines have been changed in the other window do not reflect the change. The routine touchline only pretends that count lines have been changed, beginning with line start.
The untouchwin routine marks all lines in the window as unchanged since the last call to wrefresh.
The wtouchln routine makes n lines in the window, starting at line y, look as if they have (changed=1) or have not (changed=0) been changed since the last call to wrefresh.
The is_linetouched and is_wintouched routines return TRUE if the specified line/window was modified since the last call to wrefresh; otherwise they return FALSE. In addition, is_linetouched returns ERR if line is not valid for the given window.
All routines return the integer ERR upon failure and an integer value other than ERR upon successful completion, unless otherwise noted in the preceding routine descriptions.
The XSI Curses standard, Issue 4 describes these functions.
Some historic curses implementations had, as an undocumented feature, the ability to do the equivalent of clearok(..., 1) by saying touchwin(stdscr) or clear(stdscr). This will not work under ncurses.
Note that all routines except wtouchln may be macros.