The ornamental design for a decorativepanel, as shown and described.
FIG. 1 is a front perspective view of a decorative panel showing our new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a left side elevation view thereof;
FIG. 5 is a right side elevation view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is an enlarged left side elevation view taken along the line 8-8 in FIG. 2.
The evenly dashed broken lines in the drawings illustrate portions of the decorative panel that form no part of the claimed design. The dot-dash broken lines in the drawings define the boundary of the claimed design and form no part thereof. The dot-dot-dash broken lines in the drawings delineate portions of the design that are illustrated in enlargements and form no part of the claimed design.