Esse uso do "will" para falar de algo que não funciona no presente é idiomático. É uma maneira de dizer: "Esta janela se recusa a abrir." = "This window won't open."
Se meu carro ficar em pane na rua, é natural dizer "My car won't start." Tudo mundo entenderá que estou falando do presente, é não do futuro.
Oh, I see. This is why I said "grammatically". I also already saw that in many ways and contexts. Anyway, thanks. Your comment was very helpful.
You're welcome. Verbs are influenced by context, so what looks like a reference to the future actually focuses on the present.
This is one way in which "will" is used.
Another is to say: The window doesn't open. or The window isn't opening. It's stuck.
"The window doesn't open." / "The window isn't opening." This is present.
"The window won't open". This is grammatically future, isn't?
Yes, will is the future tense of "be", but idiomatically will is also used in the sense of present tense "want". "I will not do that" can mean I won't do that because I don't want to do that (now or ever). "This window won't open" is the most idiomatic way of expressing the thought that the window is stuck, and nobody can open it. Is that clear?