// Declair
public const int WM_NCLBUTTONDOWN = 0xA1;
public const int HT_CAPTION = 0x2;

[DllImportAttribute("user32.dll")]
public static extern int SendMessage(IntPtr hWnd,int Msg, int wParam, int lParam);
        
[DllImportAttribute("user32.dll")]
public static extern bool ReleaseCapture();


// Use
private void AgentForm_MouseDown(object sender, MouseEventArgs e){
    if (e.Button == MouseButtons.Left){
                ReleaseCapture();
                SendMessage(Handle, WM_NCLBUTTONDOWN, HT_CAPTION, 0);
            }
    }
}

Move without Title

c

C#