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;
FIG. 8 is an enlarged view of the portion 8 delineated in FIG. 1;
FIG. 9 is an enlarged view of the portion 9 delineated in FIG. 2;
FIG. 10 is an enlarged view of the portion 10 delineated in FIG. 4; and,
FIG. 11 is an enlarged view of the portion 11 delineated in FIG. 6.
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 delineate portions of the design that are illustrated in enlargements and form no part of the claimed design.