MB3 117b: Closing a Window on Shabbos (313:1)

לעילוי נשמת יוסף ניסן בן יחזקאל ע"ה, Rabbi Glatt's father

Closing a door/window/skylight on Shabbos is not boneh since the building is already built, and the closure is considered temporary. Putting up a temporary curtain over a door or window on Shabbos. Using a kli as a dead bolt for a door.