Drag borderless windows form by mouse [duplicate]

This should be what you are looking for “Enhanced: Drag and move WinForms”

public partial class MyDraggableForm : Form
{
    private const int WM_NCHITTEST = 0x84;
    private const int HTCLIENT = 0x1;
    private const int HTCAPTION = 0x2;

    ///
    /// Handling the window messages
    ///
    protected override void WndProc(ref Message message)
    {
        base.WndProc(ref message);

        if (message.Msg == WM_NCHITTEST && (int)message.Result == HTCLIENT)
            message.Result = (IntPtr)HTCAPTION;
    }
    public MyDraggableForm()
    {
        InitializeComponent();
    }
}

As the blog post states, this is a way to “fool” the system. This way you don’t need to think about mouse up/down events.

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