The root cause is in sys/plugins/ncurses/c/ncurses.c, in C functions wgetwidth and wgetheight. it does not interpret properly the "maximum coordinates".

First, the actual assertion that is violated is missing in the attached reports (file #52329, file #52330 and file #52331). The reports are copied from terminal, but ncurses partially clears the screen the program exits. The real message can be seen by redirecting stderr to a file:

* Error at Run Time *: Ensure Assertion Violated.
* Error at Run Time *: Result > 0

The assertion "window /= Void" is caused by the GC disposing ncurses objects after the first assertion failure.

The real failure is in post-condition of function "witdh" from ncurses_window.e. It gives a negative window width.

Each sub-window in ncurses has 3 couples of values :

1. top-left coordinates from parent window's origin
2. top-left coordinates from screen's origin
3. "maximum coordinates"

ncurses.c wrappers interpret "maximum coordinates" as right-down coordinates from parent window's origin.

It is actually the window's size, not related to the parent window's origin.

ncurses library and documentation contradict each other about what "maximum coordinates" are ("maximums of x and y, NOT window size" in comment in curses.h - the actual C code uses them as size).

The correction is just a change in the return line :
int wgetwidth(void* win) {
   int x, y;
   getmaxyx((WINDOW*)win, y, x);
   return x - wgetleft(win);
}

in :
int wgetwidth(void* win) {
   int x, y;
   getmaxyx((WINDOW*)win, y, x);
   return x;
}

and similarly with wgetheight.

That makes all ncurses examples work.

Note that, more generally, the sub-windows API in ncurses library (getmaxyx, derwin, mvderwin, mvwin) is not reliable at all :

• subwindows are duplicated,
• subwindows are not moved,
• coordinates from parent window's origin and form screen origin's are not consistent,
• etc.

Those bugs can be seen in "movewindow" example provided with ncurses library 6.3.

It seems that the ncurses subwindow management has evolved in an instable manner.