I have found some code you have posted a while ago:

LParameter tnSrcHWND, tnDstHWND, tcData, tnIdentifier 
*Declare API functions *
Declare Long HeapAlloc in win32api Long, Long, Long 
Declare Long GetProcessHeap in win32api 
Declare Long HeapFree in win32api Long, Long, Long 
#define WM_COPYDATA 0x4A 

* Create a COPYDATASTRUCT structure *
Local lcStruct, lnMem 
lnMem = HeapAlloc( GetProcessHeap(), 0, Len(m.tcData)+12 ) 
lcStruct = ;  
toInt(m.tnIdentifier,4) + ;  
toInt(Len(m.tcData),4) + ;  
toInt(m.lnMem+12,4) + ;  
m.tcData 
Sys(2600,m.lnMem,Len(m.lcStruct),m.lcStruct)

*Send data to the other application *
Local lnRetVal 
Declare Long SendMessage in win32api Long, Long, Long, Long 
lnRetVal = SendMessage( m.tnDstHWND, WM_COPYDATA, m.tnSrcHWND, lnMem ) 

* Free up memory *
HeapFree( GetProcessHeap(), 0, m.lnMem )
Return m.lnRetVal

That code shows how to send a mesage to another application (.Net in my case).
But how do I know what m.tnDstHWND is? Is it my .Net program window handler?
Also I am bit confused: Does the c# progran need to search for a VFP window at all?
Or it is just:
protected override void WndProc(ref System.Windows.Forms.Message m)
{
switch (m.Msg)
{
case WM_COPYDATA:
// do something
break;
}
base.WndProc(ref m);
}
to process a message from VFP?


>Hi Mark,
>
>>Will I need an infinite loop in .Net in order to constantly pull data from that window?
>
>In .NET you create a simple form and then override the WndProc method:
>

>protected override void WndProc(ref System.Windows.Forms.Message m)
>{
>  switch (m.Msg)
>  {
>  case WM_COPYDATA:
>    // do something
>    break;
>  }
>base.WndProc(ref m);
>}
>

>This method is automatically called when the VFP application sends data. You don't need an infinite loop if you call Application.Run(form).