The ornamental design for a front of a pictureframe, as shown and described.
FIG. 1 is a front elevational view of a front of a picture frame; and,
FIG. 2 is a perspective view thereof.
The broken line showing of portions of the picture frame in FIGS. 1 and 2 is for illustrative purposes only, merely disclosing the entire frame which may be used, and forms no part of the claimed design.