The ornamental design for a display for a sewingmachine, as shown and described.
FIG. 1 is a front view of a display for a sewing machine;
FIG. 2 is an enlarged front view thereof; and,
FIG. 3 is another enlarged front view thereof.
The broken lines shown in the drawing disclosure are for illustrative purposes only and form no part of the claimed design. The dash-dot lines which define the bounds of the claimed design form no part thereof.