if (cursor_x > 0 && cursor_y > 0)

    if (this == TextRegion::cursor_region && cursor_x > 0 && cursor_y > 0)

    int idx = -1;
    unsigned char char_back;
    unsigned char col_back;
    if (this == TextRegion::cursor_region && cursor_x > 0 && cursor_y > 0)
    {
        idx = cursor_x + mx * cursor_y;
        char_back = cbuf[idx];
        col_back = abuf[idx];
        cbuf[idx] = '_';
        abuf[idx] = WHITE;
    }

    if (idx >= 0)
    {
        cbuf[idx] = char_back;
        abuf[idx] = col_back;
    }