tty_is_visible
if (!tty_is_visible(tty, ctx, px, py, nx, 1))
if (!tty_is_visible(tty, ctx, px, py, nx, ny))
if (!tty_is_visible(tty, ctx, ctx->ocx, ctx->ocy, 1, 1) ||
if (!tty_is_visible(tty, ctx, ctx->ocx, ctx->ocy, ctx->num, 1))