How to block double click in overridden WndProc function in Windows Forms?

Question

I have a form created in Windows Forms which is draggable wherever I click. I made it by overriding WndProc function which in turn modifies each click as it was a title bar

Answer 1

I was having the same problem today in C++. I used JaredPar's solution but with WM_NCLBUTTONDBLCLK (0x00A3) instead of WM_LBUTTONDBLCLK, that did the trick for me! It's working because the double click message is being sent from a non-client (NC) area, which is the "virtual" title bar (HTCAPTION) in this case.

Answer 2

It seems you found a solution to a problem with caused another problem that you're trying to solve. If I could suggest something simple, just a better solution to make a window drag-able:

Add InteropServices to the using declarations:

using System.Runtime.InteropServices;

And for the code:

    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();

Then go to the form's MouseDown event and paste this:

        if (e.Button == MouseButtons.Left)
        {
            ReleaseCapture();
            SendMessage(Handle, WM_NCLBUTTONDOWN, HT_CAPTION, 0);
        }

Done.

Answer 3

If you just want to stop the double click from having it's default behavior in the window for which you've overridden the WndProc then intercept the WM_LBUTTONDBLCLK message

private const int WM_LBUTTONDBLCLK = 0x0203;

...

protected override void WndProc(ref Message message) {
  if (message.Msg == WM_LBUTTONDBLCLK) {
    return;
  }

  base.WndProc(ref message);

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

Answer 4

In addition to JaredPar I would suggest don not create draggable form in that way, but handle it in 3 steps

• identify mouse down on the form
• capture mouse
• identify mouse up event

It is not a complicated to handle, and it's better, imo, then disabling a double click on the form.

For complete example of how you can do that can have a look on

Creating a Draggable Borderless Form

Answer 5

I've done the same as Jex which is working great.

private const int WM_NCHITTEST = 0x84;
private const int HTCLIENT = 0x1;
private const int HTCAPTION = 0x2;
private const int WM_LBUTTONDBLCLK = 0x00A3;

protected override void WndProc(ref Message m)
    {
        if (m.Msg == WM_LBUTTONDBLCLK)
        {
            return;
        }
        switch (m.Msg)
        {

            case WM_NCHITTEST:      
                base.WndProc(ref m);
                if ((int)m.Result == HTCLIENT)
                    m.Result = (IntPtr)HTCAPTION;
                return;
        }
        base.WndProc(ref m);
    }