The ornamental design for a window covering, as shown and described.
FIG. 1 is a front and top perspective view of a window covering shown in a fully open position;
FIG. 2 is a front view of FIG. 1;
FIG. 3 is a rear view of FIG. 1;
FIG. 4 is a top view of FIG. 1;
FIG. 5 is a bottom view of FIG. 1;
FIG. 6 is a left side view of FIG. 1;
FIG. 7 is a right side view of FIG. 1;
FIG. 8 is a front and top perspective view of FIG. 1 shown in a fully closed position;
FIG. 9 is a front and top perspective view of FIG. 1, showing the Roman blinds in front are fully open, while the roller blinds in behind are fully closed; and,
FIG. 10 is a front and top perspective view of FIG. 1, showing the Roman blinds in front are fully closed, while the roller blinds in behind are fully open.
The broken lines in the drawings represent portions of the window covering that form no part of the claim.