The ornamental design for an operatingdisplaypanel, as shown and described.
FIG. 1 is a top front perspective view of a new design for an operating display panel;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a left elevation view thereof, which is a mirror image of a right elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a bottom plan view thereof; and,
FIG. 6 is a top plan view thereof.
The broken lines showing particular elements of the operating display panel are included for illustrative purposes only and form no part of the claimed design.