Get a String from an IntPtr from a WPARAM

[komalo]

i am using SendMessage to send a message with a LPTSTR in WPARAM from a dll to my vb.net form and i get it by overriding WndProc but the problem is when using Marshal.PtrToStringAuto on the WPARAM it doesn't work, the strange thing is that if i monitor WM_SETTEXT of the form and use PtrToStringAuto to get the string from LPARAM it works, i guess mine doesn't work that's because the dll is loaded by other application.


C++ DLL Proc

LRESULT CALLBACK CallWndProc(int nCode,WPARAM wParam,LPARAM lParam)
{

	if( (lParam!=NULL) && (nCode == HC_ACTION))
	{
		CWPSTRUCT *CwpStruct = (CWPSTRUCT *) lParam;
		switch(CwpStruct->message)
		{
			case WM_SETTEXT:
				SendMessageTimeout(hWnd,WM_USER + 2,WPARAM(CwpStruct->lParam),LPARAM(CwpStruct->hwnd),SMTO_ABORTIFHUNG,100,0);
				break;
		}
	}
	return CallNextHookEx(hHook,nCode,wParam,lParam);
}

VB.NET Code

Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        Try
                Select Case m.Msg
                    Case MyMsgs.WM_SETTEXT
                    'i successfully get the pointer but can't get the text
                        Me.Text = System.Runtime.InteropServices.Marshal.PtrToStringAuto(m.WParam)
        Catch ex As Exception
            Debug.WriteLine("Error Messages : " & ex.Message )
        Finally
            MyBase.WndProc(m)
        End Try
End Sub