line = newline;
unsigned long *lineptr(int y, int lineno){    unsigned long *line, *newline;    tree234 *whichtree;    int treeindex;    if (y >= 0) {	whichtree = screen;	treeindex = y;    } else {	whichtree = scrollback;	treeindex = y + count234(scrollback);    }    line = index234(whichtree, treeindex);    /* We assume that we don't screw up and retrieve something out of range. */    assert(line != NULL);    newline = resizeline(line, cols);    if (newline != line) {	delpos234(whichtree, treeindex);	addpos234(whichtree, newline, treeindex);    }    return line + 1;}