how do i close a single window without closing firefox

I already asked this question once and you just brought me back to ask the same question again. I want to close all the tabs in a window like i could in the previous version of firefox. i do not want to exit firefox. you give me the option to close other tabs, or to close current tab if other tabs in the window are open. i want to close all tabs, including the last tab in a window without exiting firefox please.