You are absolutely wright about the hooks that AV is doing. I'm not sure that it's a bug in it's checking, however.
I'm not saying that it's some kind of IA bug, no. Please, forgive me if it was sounded like that.
All I ask is that if it will be possible to implement a custom timeout set, that will be great.
You also said that IA has it's own download engine. It would be great to have opportunity to select which engine to use either. A precompiler variable would be sufficient for this, i think.
However, if it will be possible to select the engine at runtime, that will be fantastic. If one engine fails with download, then another can succeed. The probability that both engine will succeed, imo, is greater than the probability of success of single download engine.
As I said before, it would be great to have such features in the box. This will make software more flexible, in certain situations it will help us, developers, using IA, to outcome problems, which cannot be predicted during IA development. This is just a suggestion
Have a nice day!

