A license holder or agent or employee of the license holder may sell alcoholic beverages only in a room having at least one plain glass window or door that allows an individual standing on the outside to observe the interior of the licensed premises during all hours of operation. During all hours of operation, the view afforded by the window or door may not be obstructed. A license holder may install a protective covering over an exterior door or window of the licensed premises if the covering is: used only when the licensed premises is not occupied; designed to protect the licensed premises from unlawful intrusion or destruction; and secured only from the exterior of the licensed premises. This subsection does not prevent an inspection and search of the licensed premises under § 6–202 of this article. A person who violates this section is guilty of a misdemeanor and on conviction is subject to a fine not exceeding $250 or imprisonment or both.