FIG. 1 is a perspective view of a corner panel for shower enclosure showing our new design; FIG. 2 is a top plan view thereof, taken along lines 2—2 of FIG. 1; FIG. 3 is a cross-sectional view taken along lines 3—3 of FIG. 2; FIG. 4 is a top plan view thereof; FIG. 5 is a side view thereof; and, FIG. 6 is a front view thereof. The broken line showing of portions of the shower enclosure is for illustrative purposes only and forms no part of the claimed design.