Ok, if i understand correctly, everyone agrees there should be some kind of transfer status. The only thing left is how it should look like.
But as a seperate windows (like a toast-popup), that becomes messy... i have seen that with other messengers and if you have multiple chatwindows, with a filetransfer from each pal, it will become very messy and hard to tell which is from whom.
afterall, we don't want too many open windows on our desktop
But perhaps it can be made in several stages in the active chatwindow, that can be selected in the options menu on which one you prefer.
1/ a simple icon for each transfer in the chatwindow (for thos who don't want to mess up their window)
2/ a progressbar
3/ a full detailed bar/section in the chatwindows
perhaps when it's begun with step 1, you can pulldown, more options or properties.... and that with every stage....
Just put the different stages in the options menu and let the user decide wich one they prefer (even if you prefer toast popups). That way, everyone is happy