How to create a form with a border, but no title bar? (like volume control on Windows 7)

Question

In Windows 7, the volume mixer windows has a specific style, with a thick, transparent border, but no title bar. How do i recreate that window style in a winforms window?

I tried setting Text to string.Empty, and ControlBox to false, which removes the titlebar, but then the border also disappears:

Answer 1

form.Text = string.Empty;
form.ControlBox = false;
form.FormBorderStyle = FormBorderStyle.SizableToolWindow;

For a fixed size window, you should still use FormBorderStyle.SizableToolWindow, but you can override the form's WndProc to ignore non-client hit tests (which are used to switch to the sizing cursors):

protected override void WndProc(ref Message message)
{
    const int WM_NCHITTEST = 0x0084;

    if (message.Msg == WM_NCHITTEST)
        return;

    base.WndProc(ref message);
}

If you want to really enforce the size, you could also set MinimumSize equal to MaximumSize on the form.

Answer 2

Since "This edit was intended to address the author of the post and makes no sense as an edit. It should have been written as a comment or an answer." I present an edit to Chris' answer as a new answer.

The code his answer works as described - except that it also prevents any client area mouse event to occur. You need to return 1 (as in HTCLIENT) to fix that.

protected override void WndProc(ref Message message)
{
    const int WM_NCHITTEST = 0x0084;
    const int HTCLIENT = 0x01;

    if (message.Msg == WM_NCHITTEST)
    {
        message.Result = new IntPtr(HTCLIENT);
        return;
    }

    base.WndProc(ref message);
}

Answer 3

form.FormBorderStyle = FormBorderStyle.Fixed3D;