A carton comprises a plurality of adjoined panels that define an interior space, including a front panel and a back panel opposite one another, and a first side panel and a second side panel opposite one another, at least one of which is a movable panel operative for being moved between a first position and a second position, and a heat-shrink patch at least partially joined to the movable panel on a side of the movable panel facing the interior space, the heat-shrink patch being operative for shrinking in response to heat so that shrinking the heat-shrink patch moves the movable panel from the first position to the second position.