The ornamental design for a shower stallinterior, as shown and described.
FIG. 1 is a perspective view, from front upper right, of a shower stall interior showing my new design.
FIG. 2 is a front view of a shower stall interior showing my new design.
FIG. 3 is a perspective view, from front upper left, of a shower stall interior showing my new design; and,
FIG. 4 is a view of a shower stall interior, from right of the shower stall, with the right wall removed for clarity.
Note that the claim also covers the new design embodied in a shower stall interior that is a mirror image of that shown in the figures. Note also that this application is intended to disclose a design where any one or more features of the shower stall interior shown, in the initial filing, in solid line, is converted to broken line.