to someone familiar with internal working of strlib.asm:
Does the allocated blocks really have to be zeroed? (with HEAP_ZERO_MEMORY)
because if no, then it's just unnescesary slowdown

No, it works well without it. But I don't think it slows down memory allocation a lot. It would be only 'rep stosd', right?

Win2k and later ignore this parameter and always zero allocated memory.

well, so i leave it out. Maybe it doesn't slow too much, but itdoes. we can easily clear memory ourselves when we need (and faster)

revolution: typical example of their unability to code. i believe they had bugs because of forgetting to clear memory, so they solved it this way. just like the one, when callback procedure returns to caller address always, regardless what is on the stak.

Actually it is for security to ensure that no information can leak from one process to another by using memory allocations.

that can be it too...
i believe that stack tricking is for security too

What is "stack tricking"?

that isn't it's real name.
if you mess stack in winXP callback procedure it returns to real address somehow anyway. i had ugly bug with that, i messed stack, but it still worked on some machines and crashed on others. and it was directx project so crash wasn't very nice, especially on older OSes.