The ornamental design for a windowshutterstile, as shown and described.
FIG. 1 is a perspective view of a window shutter stile, showing my new design in condition of use on opposite sides of a window shutter;
FIG. 2 is a perspective view of the window shutter stile thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a left end elevation view thereof;
FIG. 5 is a front side elevation view thereof;
FIG. 6 is a right end elevation view thereof;
FIG. 7 is a rear side elevation view thereof; and,
FIG. 8 is a bottom plan view thereof.
The broken line showing of shutter slats, slat end pieces, and a shutter control rod in FIG. 1 is for illustrative purposes only and forms no part of the claimed design.