The ornamental design for a shower controlpanel, as shown and described.
FIG. 1 is a perspective view of a shower control panel showing our design;
FIG. 2 is a front elevation view;
FIG. 3 is a rear elevation view;
FIG. 4 is a right side elevation view;
FIG. 5 is a left side elevation view;
FIG. 6 is a top plan view; and,
FIG. 7 is a bottom plan view.
The broken-line disclosure in the views represents portions of the shower control panel in which the claimed design is embodied, but which form no part of the claimed design.