str_idPopup ID hashed in the current ID stack; null uses the last item ID for item popups, or the built-in context ID for window/void popups.
popup_flagsImGuiPopupFlags options controlling this operation; combine compatible flag bits with |.
True when this scope is open/active and its contents may be submitted. Call EndPopup() only when true; on false, skip both contents and the matching end.
Open and begin a context popup for the preceding item.