Constraining multiple stack windows within one stack window

[Glen Bojsza]

I was wondering if anyone can tell me how to constrain one stack
window within the given area of another stack window.

An analogy would be microsoft word and opening several documents ...
the documents are constrained by the current size of the word
window...the document can be maximized or sized  .  In my case I want
to open several different stacks.

Hopefully, I've explained this correctly.

thanks,

Glen