Ok.. if the window is resizable, then I don't really care.
As for your
problematic situation, I'm sorry but I don't fully understand.... (am I the only one ?)
Anyway, if saying that
"saving the last action you've made" makes sense for you, I'd also add :
"Add a warning message if such cases happen"
In other words, if it's just a problem of saving priority, make it save the last modified thing.
It's just like opening the same file 2 times, editing and saving on, then saving the other...
It'll be our fault, so just don't care about it..
Oh! and if needed, we still can launch your program on the same file twice... (act it as a viewer)