Example of using EM_STREAMOUT with c# and RichEditBox

Question

Hello

i trying to get a text from a RichEdit field with WM_GETTEXT, but i run into some problems, so I found EM_STREAMOUT, this is especially for RichEdit. I found this code and played a little bit with it, but i can't get them to work:

delegate uint EditStreamCallback(IntPtr dwCookie, IntPtr pbBuff, int cb, out int pcb);

struct EDITSTREAM
{
public IntPtr dwCookie;
public uint dwError;
public EditStreamCallback pfnCallback;
}

[DllImport("user32.dll", CharSet=CharSet.Auto)]
static extern IntPtr SendMessage(HandleRef hwnd, uint msg, uint wParam, ref EDITSTREAM lParam);

maybe someone have a working example of using this in c#?

thx david