🚀 go-pugleaf

m > My are questions:
m > 
m >      1) Is there any system penalty for always using shared memory?
m >         For example, is it a limited resource or is it more costly
m >         to access?
Think so, but no quite sure.
m >      2) Is GMEM_DDESHARE really even necessary for Windows 3.0 in standard
m >         or enhanced modes or Windows 3.1?  Or is it just a throw back from
m >         EMS banked memory and real mode?
No, there is really different handling. For example "normal" global memory 
allocated inside a DLL belongs to the app using the DLL, but 
"GMEM_DDESHARE"-memory allocated inside a DLL belongs to the DLL!

m >      3) Can I send pointers to shared memory between apps and use them
m >         directly?
Yes, with Win 3.x.
m >      4) Is the following scenario a still a restriction under 3.1 or 3.0
m >         in standard and enhanced:
m > 
m >           -- App A creates shared memory and writes to it
m >           -- App A sends a message to App B containing the handle/pointer
m >               of the shared memory
m >           -- App B reads the shared memory, does something interesting,
m >              and then writes the results to the same shared memory
m >           -- App B sends a message to App A saying "all done, read the
m >              the shared memory that you sent me"
m >           -- App A reads it
m > 
m >         The question is does App A see anything useful.
Yes, with Win 3.x it will work fine. But be aware, with future 
32-Bit-Windows-Version it will not be allowed to pass memory-references 
directly between apps. The apps will have strictly separeted adress spaces! In 
this environment you will have to a real DDE-protocol via DDESendMessage and so 
on.

Greetings Martin