In carton boxes of that particular dispenser type, where the broad front side (2) of the box exhibits a dispenser opening, which is internally covered by a slide panel (18) with an opening (20), the slide panel is displaceable into a dispensing position by an outward pivoting of an associated end flap (26) of the box. The slide panel is prevented from falling into the box in that it has laterally projecting side flaps (28) which ride on the top edges of inner, upright side wall portions (8) of the box, this riding engagement being secured by the side flaps being folded down along the upper, exterior area of the side wall portions (8). Outer side wall portions (12) folded down from the front or top panel (2) are at their lower edge area welded or glued to the root zone of the inner, upright side wall portions. The associated folding of the said side flaps (28) may result in an inward pivoting of the inner side wall portions (8), which in turn disables a perfect face-to-face engagement in the lower joining zone (A, B) between the side wall portions. According to the invention this drawback is eliminated in arranging for a longitudinal cutting line (C) near the middle of the inner side wall portion (8), such that by the folding down of the side flap (28) it will only be the strip area above this line which is forced inwardly, while the remaining lowermost strip area can be joined safely face to face with the outer side wall portion (12).