The ornamental design for a giftbag with detachableactivity surface, as shown and described.
FIG. 1 is a top front perspective view of a gift bag with detachable activity surface showing my new design;
FIG. 2 is a front elevation view thereof, with the rear elevation view being a mirror image thereof;
FIG. 3 is a right elevation view thereof;
FIG. 4 is a left elevation view thereof;
FIG. 5 is a top elevation view thereof; and,
FIG. 6 is a bottom elevation view thereof.
The broken lines shown in the drawings that illustrate crayons form no part of the claimed design.
The broken lines in FIGS. 1 and 2 showing the gift bag with detachable activity surface in use illustrates perforations in the front surface of the bag.