Make a borderless form movable?

It worked for Me.

    private Point _mouseLoc;

    private void Form1_MouseDown(object sender, MouseEventArgs e)
    {
        _mouseLoc = e.Location;
    }

    private void Form1_MouseMove(object sender, MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left)
        {
            int dx = e.Location.X - _mouseLoc.X;
            int dy = e.Location.Y - _mouseLoc.Y;
            this.Location = new Point(this.Location.X + dx, this.Location.Y + dy);
        }
    }

https://social.msdn.microsoft.com/Forums/vstudio/en-US/d803d869-68e6-46ff-9ff1-fabf78d6393c/how-to-make-a-borderless-form-in-c?forum=csharpgeneral

This bit of code from the above link did the trick in my case :)

protected override void OnMouseDown(MouseEventArgs e)  

{
      base.OnMouseDown(e);
      if (e.Button == MouseButtons.Left)
      {
        this.Capture = false;
        Message msg = Message.Create(this.Handle, 0XA1, new IntPtr(2), IntPtr.Zero);
        this.WndProc(ref msg);
      }
}

Since some answers do not allow for child controls to be draggable, I've created a little helper class. It should be passed the top level form. Can be made more generic if desired.

class MouseDragger
{
    private readonly Form _form;
    private Point _mouseDown;

    protected void OnMouseDown(object sender, MouseEventArgs e)
    {
        _mouseDown = e.Location;
    }

    protected void OnMouseMove(object sender, MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left)
        {
            int dx = e.Location.X - _mouseDown.X;
            int dy = e.Location.Y - _mouseDown.Y;
            _form.Location = new Point(_form.Location.X + dx, _form.Location.Y + dy);
        }
    }
    public MouseDragger(Form form)
    {
        _form = form;

        MakeDraggable(_form);            
    }

    private void MakeDraggable(Control control)
    {
        var type = control.GetType();
        if (typeof(Button).IsAssignableFrom(type))
        {
            return;
        }

        control.MouseDown += OnMouseDown;
        control.MouseMove += OnMouseMove;

        foreach (Control child in control.Controls)
        {
            MakeDraggable(child);
        }
    }
}

I'm expanding the solution from jay_t55 with one more method ToolStrip1_MouseLeave that handles the event of the mouse moving quickly and leaving the region.

private bool mouseDown;
private Point lastLocation;

private void ToolStrip1_MouseDown(object sender, MouseEventArgs e) {
    mouseDown = true;
    lastLocation = e.Location;
}

private void ToolStrip1_MouseMove(object sender, MouseEventArgs e) {
    if (mouseDown) {
        this.Location = new Point(
            (this.Location.X - lastLocation.X) + e.X, (this.Location.Y - lastLocation.Y) + e.Y);

        this.Update();
    }
}

private void ToolStrip1_MouseUp(object sender, MouseEventArgs e) {
    mouseDown = false;
}

private void ToolStrip1_MouseLeave(object sender, EventArgs e) {
    mouseDown = false;
}

Adding a MouseLeftButtonDown event handler to the MainWindow worked for me.

In the event function that gets automatically generated, add the below code:

base.OnMouseLeftButtonDown(e);
this.DragMove();

Form1(): new Moveable(control1, control2, control3);

Class:

using System;
using System.Windows.Forms;

class Moveable
{
    public const int WM_NCLBUTTONDOWN = 0xA1;
    public const int HT_CAPTION = 0x2;
    [System.Runtime.InteropServices.DllImportAttribute("user32.dll")]
    public static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);
    [System.Runtime.InteropServices.DllImportAttribute("user32.dll")]
    public static extern bool ReleaseCapture();
    public Moveable(params Control[] controls)
    {
        foreach (var ctrl in controls)
        {
            ctrl.MouseDown += (s, e) =>
            {
                if (e.Button == MouseButtons.Left)
                {
                    ReleaseCapture();
                    SendMessage(ctrl.FindForm().Handle, WM_NCLBUTTONDOWN, HT_CAPTION, 0);
                    // Checks if Y = 0, if so maximize the form
                    if (ctrl.FindForm().Location.Y == 0) { ctrl.FindForm().WindowState = FormWindowState.Maximized; }
                }
            };
        }
    }
}

I tried the following and presto changeo, my transparent window was no longer frozen in place but could be moved!! (throw away all those other complex solutions above...)

   private void Window_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        base.OnMouseLeftButtonDown(e);
        // Begin dragging the window
        this.DragMove();
    }