A drive-in or convenience type window shall be permitted use provided there shall be a permanent canopy or portico attached to the building, covering the vehicle, and the vehicular traffic flow from such window is restricted so that there is no access to the on site parking areas and the vehicular traffic is channeled directly onto a public street. The traffic pattern for the proposed window shall be reviewed by the Planning Board and the Police Department prior to the granting of approval for such window. For the purpose of this paragraph, a drive-in or convenience type window shall be deemed to be an accessory use provided that the majority of the business is conducted within the confines of the building.