static extern IntPtr CallWindowProc(WndProcDelegate lpPrevWndFunc, IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

Private Shared Function CallWindowProc(lpPrevWndFunc As WndProcDelegate, hWnd As IntPtr, Msg As UInteger, wParam As IntPtr, lParam As IntPtr) As IntPtr

WndProcDelegate

When you call this function, the WndProc function must respond to the WM_NCCREATE message by returning TRUE. If it does not, the creation process will fail. A null handle will be returned from CreateWindowEx and GetLastError will return 0. See MSDN on WM_NCCREATE (http://msdn.microsoft.com/en-us/library/ms632635.aspx) and also WM_CREATE (http://msdn.microsoft.com/en-us/library/ms632619.aspx). You can have your WndProc call DefWindowProc, which will take care of this issue.

            wndclass.lpfnWndProc = (WndProc)((hWnd, message, wParam, lParam ) => {

    protected override void WndProc(ref Message m)

        base.WndProc(ref m);

     GWL_WNDPROC =    (-4),

     GWL_WNDPROC = -4

     GWL_WNDPROC =    (-4),

     GWL_WNDPROC = -4

        Public lpfnWndProc As IntPtr

        .lpfnWndProc = IntPtr.Zero

               "lpfnWndProc: " & .lpfnWndProc.ToString & vbCrLf & _

    private static IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)

/// protected override void WndProc(ref Message m)

///      base.WndProc(ref m);

protected override void WndProc(ref Message m)

    base.WndProc (ref m);

} //WndProc

    protected override void WndProc(ref Message m)

        base.WndProc(ref m);

Use the version that takes an IntPtr as last parameter and pass it IntPtr.Zero if you are going to handle the WM_TIMER message in your own override of WndProc.

Use the version that takes a delegate as last parameter if you don't explicitly handle the WM_TIMER message or if you don't override WndProc. In that case DefWndProc will invoke your callback when the time-out value elapses.

///         <term>WH_CALLWNDPROC (4)</term>

///         destination window procedure. For more information, see the CallWndProc hook procedure.

///         <term>WH_CALLWNDPROCRET (12)</term>

///         <term>WH_CALLWNDPROC (4)</term>

///         <term>WH_CALLWNDPROCRET (12)</term>

    Public lpfnWndProc As IntPtr

    .lpfnWndProc = IntPtr.Zero

           "lpfnWndProc: " & .lpfnWndProc.ToString & vbCrLf & _

    Protected Overrides Sub WndProc(ByRef m As Message)

        MyBase.WndProc(m)

        protected override void WndProc(ref Message m)

            base.WndProc(ref m);

delegate IntPtr WndProcDelegate(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);

Delegate Function WndProcDelegate(Byval hWnd As IntPtr, Byval msg As UInteger, Byval wParam As IntPtr, Byval lParam As IntPtr) As IntPtr

    class SessionChangeHandler : Control // allows us to override WndProc

        protected override void WndProc(ref Message m)

            base.WndProc(ref m);

     GCLP_WNDPROC       = -24,

     GCLP_WNDPROC       = -24

     GCLP_WNDPROC       As Long = -24

     WH_CALLWNDPROC = 4,

     WH_CALLWNDPROCRET = 12,

     WH_CALLWNDPROC = 4

     WH_CALLWNDPROCRET = 12

     GWL_WNDPROC = -4,

     GWL_WNDPROC = -4

     GWL_WNDPROC As Long = -4

        protected override void WndProc(ref Message m)

            base.WndProc(ref m);

        protected override  void WndProc(ref Message m)

                    base.WndProc(ref m);

delegate IntPtr WndProc (IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);

Delegate Function WndProc (ByVal hWnd As IntPtr, ByVal msg As Integer, _

private delegate IntPtr WndProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);

Private Delegate Function WndProc(ByVal hWnd As IntPtr, ByVal msg As UInteger, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As IntPtr

Check with WindowsMessages for a list of most (if not all) of the constants that will be passed in as messages to the WndProc method.

protected override void WndProc(ref Message m)

   base.WndProc(ref m);

   public WndProc lpfnWndProc;

   Public lpfnWndProc As WndProc

WndProc, ClassStyles

• lpfnWndProc

• Pointer to the window procedure. You must use the CallWindowProc function to call the window procedure. For more information, see WndProc.
The CallWindowProc API
11/23/2012 7:05:10 PM - -67.128.30.210
A delegate for window procedure callbacks (handlers).
7/31/2009 12:04:10 PM - -92.224.233.194

    public IntPtr lpfnWndProc; // not WndProc

   Public lpfnWndProc As IntPtr

WndProc, ClassStyles

• lpfnWndProc

• Pointer to the window procedure. You must use the CallWindowProc function to call the window procedure. For more information, see WndProc.
The CallWindowProc API
11/23/2012 7:05:10 PM - -67.128.30.210
A delegate for window procedure callbacks (handlers).
7/31/2009 12:04:10 PM - -92.224.233.194

static readonly int GWL_WNDPROC    = -4;

Public Const GWL_WNDPROC    = -4

     GWL_WNDPROC = -4,

// Override the WndProc function in the form

protected override void WndProc(ref Message m)

    base.WndProc(ref m);

' Override the WndProc function which is called when the play function ends

Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)

     MyBase.WndProc(m)

Things like RegisterWindowClass and GetClassInfo using the WNDCLASS structure in different ways requires creating separate structures with different field types in order to satisfy the marshaller (The WndProc pointer as a raw IntPtr in some cases, or as a method pointer in other cases). I can see that the params for GetClassInfo and RegisterWindowClass do take different structure types, but those types do not appear to be documented here.