New windows are very useful, for people that actually work with a solution, they're nice to to compare, have several foundset etc.
And hence the "new window" menu item is just great.
But, you may soon deal with several windows, and then it's not easy to manage.
So, if the user (of course dev could control this to allow it or not), needs to, he would select the rename window menu item and be able to rename his windows.
That way, he'll be able to better manage and find windows.
That's specially handy working in list/table view with many records, and you want to have different foundsets or subset of foundsets
For instance, the user may label this : available sku, sku with high margin, skus with low margins
Being built-in, it would ba available everywhere (unless forbidden by dev), and that's very straightforward to understand even for newbies
P.S : I know some the one design window trend : that's not the subject here