How to make an object stay in the same position relative to another object

Question

I have a text box and I want to leave it in the same place relative to the image

Answer 1

One of the ways is with a FlowLayoutPanel

A test with
Anchor : Bottom, Right
and
Margin 50; 50; for the TextBox
=>

Answer 2

You can also override WM_SIZING .
Random test =>

private void MoveSize()
{
    // Resize/Move controls as you want     
    pictureBox1.Left = (this.ClientSize.Width - pictureBox1.Width) / 2;
    pictureBox1.Top = (this.ClientSize.Height - pictureBox1.Height) / 2;
    // textBox1 relative to pictureBox1
    textBox1.Left = pictureBox1.Left + 100;
    textBox1.Top = pictureBox1.Bottom + 20;
}

public const int WM_SIZING = 0x0214;

protected override void WndProc(ref Message m)
{
    base.WndProc(ref m);
    if (m.Msg == WM_SIZING)
    {
        MoveSize();
        m.Result = (IntPtr)1;
    }
}