1 using System;
 2 using System.Collections.Generic;
 3 using System.ComponentModel;
 4 using System.Data;
 5 using System.Drawing;
 6 using System.Linq;
 7 using System.Text;
 8 using System.Windows.Forms;
 9 
10 namespace NoBoarder
11 {
12     public partial class FormParent : Form
13     {
14         public FormParent()
15         {
16             InitializeComponent();
17         }
18 
19         protected bool isMouseDown = false;
20         protected Point FormLocation;
21         protected Point mouseOffset;
22 
23         private void FormParent_MouseDown(object sender, MouseEventArgs e)
24         {
25             if (e.Button == MouseButtons.Left)
26             {
27                 isMouseDown = true;
28                 FormLocation = this.Location;
29                 mouseOffset = Control.MousePosition;
30 
31             }  
32         }
33 
34         private void FormParent_MouseMove(object sender, MouseEventArgs e)
35         {
36             int x = 0;
37             int y = 0;
38             if (isMouseDown)
39             {
40                 Point pt = Control.MousePosition;
41                 x = mouseOffset.X - pt.X;
42                 y = mouseOffset.Y - pt.Y;
43                 this.Location = new Point(FormLocation.X - x, FormLocation.Y - y);
44             }  
45         }
46 
47         private void FormParent_MouseUp(object sender, MouseEventArgs e)
48         {
49             isMouseDown = false; 
50         }
51     }
52 }

1 private void button1_Click(object sender, EventArgs e)
2         {
3             FormSon f = new FormSon();
4             f.Show();
5             this.Hide();
6         }

1 public partial class FormSon : FormParent //!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2     { 
3         public FormSon()
4         {
5             InitializeComponent();
6         }
7     }