Question

I have a situation where I would like to move a windows form by holding right mouse button on it’s client area; the form it’s borderless as i’ve stated.

I would like to move it “natively” (if possible, otherwise other answers are ok too). I mean the way it behaves when you hold left mouse button on the titlebar (with mouse-move and things like that I get a lot of strange behaviours, but maybe it’s just me).

I’ve read around a lot of things and this post looks helpful

http://social.msdn.microsoft.com/Forums/en-US/csharpgeneral/thread/b9985b19-cab5-4fba-9dc5-f323d0d37e2f/

I tried various way to use that and watched through http://msdn.microsoft.com/en-us/library/ff468877%28v=VS.85%29.aspx to find other useful things and WM_NCRBUTTONDOWN came in my mind, however the wndproc doesn’t detect it, maybe because it’s handled by the form?

Any suggestion are appreciated, thanks

Francesco

Answer 1

public partial class DragForm : Form
{
    // Offset from upper left of form where mouse grabbed
    private Size? _mouseGrabOffset;

    public DragForm()
    {
        InitializeComponent();
    }

    protected override void OnMouseDown(MouseEventArgs e)
    {
        if( e.Button == System.Windows.Forms.MouseButtons.Right )
            _mouseGrabOffset = new Size(e.Location);

        base.OnMouseDown(e);
    }

    protected override void OnMouseUp(MouseEventArgs e)
    {
        _mouseGrabOffset = null;

        base.OnMouseUp(e);
    }

    protected override void OnMouseMove(MouseEventArgs e)
    {
        if (_mouseGrabOffset.HasValue)
        {
            this.Location = Cursor.Position - _mouseGrabOffset.Value;
        }

        base.OnMouseMove(e);
    }
}