In latest stable release and now in svn (at least it was some weeks ago) the autofocus behaviour has changed. Now, there is only two options - newly created windows ALWAYS get focus, or NEVER. In stable, it bahved like I wanted it to - new applications didn't get focus, but windows created by active windows got focus (for example gaim new conversation windows and firefox warning/confirmation windows). It is coming really annoying, as I have several times killed firefox, to realise that it was just waiting me to clik a OK button in a dialog, that was created unfocused and was therefore hidden behind main window, and didn't appear in taskbar either. There is already a feature request for giving newly created windows URGENT hint, but at the FF example, that wouldn't help. So, I would like to get a third option in xfwm4 settings, to only give focus to windows, that were created by active windows. I hope it is doable, or there is a workaround for that.
Unfocused windows are not placed on top of focused window anymore for obvious usability concerns. There is no plan to revert this. As there is no way to tell a window was created by another window (as you asked), there is not much I can do about that. Actually, what you describe has not changed, the problem is that Firefox doesn't use the standard transient_for hint that xfwm4 honors (including the transient_for group of windows when the transient_for hint is set to the root window) for its confirmation dialog. To make a long story short, xfwm4 will place transient_for on top of windows of the same group, but Firefox doesn't use it for it confirmation dialog.
I was not talking about raising created & unfocused windows, but that's irrelevant I guess. I see... I don't know anything about window manager internals, but I really hope that some better focus stealing prevention will be implemented soon. KDE for example has (at least had ages ago) slider to set focus stealing strictness... You said about something about group of windows and its root window, so I guess that gaim main window is the root window and conversation windows are in the same group, righ? what about allowing same group (that is active?) windows to get focus? I could have misunderstood something tho..