There is one client, and it uses LoadLibrary to get the DLL (which installs a global keyboard hook).

As long as the client is in focus, the DLL can call a callback function which the client provides it with. If however the client is not in focus, the callback never returns.

The trouble is, what I understand from the MSDN, the DLL is duplicated many times (once for each running application) to handle the keyboard hooking....

...I hope this isn't off topic as it refers to DLLs. I would not find a Windows-specific programming forum on this site.

I suspect this question is less about DLLs and more about how to share data between applications using C++ (but perhaps even that is OS-specific) :(

Hello all. I'm writing a Push To Talk radio program. As such I have a DLL that uses SetWindowsHookE x to set a callback function. This works, and is called when keyboard events take place.

Client programs using this DLL wish to know when a keyboard event takes place (even if said client program is not in the foreground).

So in my DLL I store a function pointer in a shared data section), and the DLL allows the clients...