Move a form using MouseDown() even if it doesn't have a titlebar

moveFormWithoutTitlebar.cs

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;

/*
Shows how to move the form without using a Title Bar to drag the form around the screen. 
This can be adapted for custom forms (those with a customized picture box image overlaying the form, 
and FormBorderstyle set to 'None' by simply changing Form1_MouseDown() to pictureBox1_MouseDown()...
*/

namespace MoveFormWithoutTitlebar {
    public partial class Form1 : Form {

        
        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();
        

        public Form1() {
            InitializeComponent();
        }

        private void Form1_MouseDown(object sender, MouseEventArgs e) {
            if (e.Button == MouseButtons.Left) {
                ReleaseCapture();
                SendMessage(Handle, WM_NCLBUTTONDOWN, HT_CAPTION, 0);
            }
        }
    }
}