That System Events Dictionary contained a wealth of stuff I didn't know about, including the answer to my question. Thanks very much for the reference.
Being that System Events is typically one of the more/most often calls being made when using AppleScript looking into its Dictionary or any Dictionary for that matter is SOP when programing with AppleScript and information like this is readily available in AppleScript centric forums/web sites so I would find that this is only a revelation to someone that hasn't done much programmer to begin with. The File > Open Dictionary... command in AppleScript is there for a very good reason and it's not rocket science.
I still respectfully disagree about this being the right place to ask that question, over and above the fact that it produced the Right Answer, which is a pretty good argument by itself.
First of all not only is AppleScript not supported by Fusion any coding in AppleScript to ascertain who the topmost window belongs to has nothing to do with Fusion from a programmatic standpoint as the target one is look for is going to be user defined and the same code is going to be interchangeable by substituting whatever the target might be for the target at that point in the code even if it happed to be a window belonging to Fusion or any other Applications window for that matter.
Secondly I never said that this wasn't the right place to to ask and the main thrust of my first reply was two fold to let you know that AppleScript isn't supported in Fusion and that AppleScript centric forums/web sites are typically a better places to be looking for help with AppleScript. That certainly doesn't mean that you will not find something useful here nor does it mean you can't ask either.
With no offense indented to Tom and keeping in mind that you explicitly said "but it's really not an Applescript question" even though you asked "How can I tell in Applescript..." then that negates Toms answer as being correct much less the fact that this same information is already out in the Internet and with a little searching it could/would have been found other then having it being repeated again here. I know because I've seen that same information out on the Internet before by searching for the answer to a question similar to yours.
Don't get me wrong I'm glad that if what was presented in the forum helps you solve your problem however as a programmer myself I can assure you that every bit of code I've use as an example of what I wanted to program I've found much quicker in forums centric to the language I'm programing in, and that goes for all the AppleScripts scripts I've written that are used with Fusion as well, then in a forum such as in this case and is why suggesting you search it's a very valid reply in a case such as this.
But that question could not ever arise if I was working only in Windows, or only in OSX. The only time that question has any relevance is when I'm working on both at once under Fusion or one of it's lesser kin. So where better to ask a question about working on two OS's side by side? Who has more experience doing that than this group?
Again enumerating windows and who owns them and acting according is SOP and how that is done programmatically the structure of a function to do that should work regardless of the fact that the windows belongs to Fusion or any other application. In other words writing reusable code and passing functions variables is a typically considered a better and more professional approach then hard coding something that may only be good for one thing and in that respect AppleScript doesn't care whether the topmost window is a window belonging to Fusion or iTunes for that matter. So as far as I'm concerned your question was more relevant to AppleScript and programming in general then it is specifically to Fusion.
