---

void DrawAgain()
{
    int x = 0;
    int y = 0;
    int maxH = 0;

    foreach (PictureBox p in pics)
    {
        if (x + p.Width >= 1000)
        {
            x = 0;
            y += maxH;
            maxH = 0;
        }

        p.Left = x;
        p.Top = y;

        x += p.Width;

        if (p.Height > maxH)
            maxH = p.Height;
    }
}



private void button1_Click(object sender, EventArgs e)
{
    pics.Sort((a, b) => a.Width.CompareTo(b.Width));

    DrawAgain();
}

private void button2_Click(object sender, EventArgs e)
{
    pics.Sort((a, b) => a.Height.CompareTo(b.Height));

    DrawAgain();
}