The ornamental design for a window, as shown and described.
FIG. 1 is a left front side perspective view of the window;
FIG. 2 is a front side view of the window shown in FIG. 1;
FIG. 3 is a bottom side view of the window shown in FIG. 1;
FIG. 4 is a top side view of the window shown in FIG. 1;
FIG. 5 is a right side view of the window shown in FIG. 1;
FIG. 6 is a left side view of the window shown in FIG. 1;
FIG. 7 is a cross-sectional view of the window taken along line 7-7 in FIG. 1; and,
FIG. 8 is a back side view of the window shown in FIG. 1.
The portions of the window shown in dashed lines, and any surfaces of the design not shown, including interior surfaces, form no part of the claimed invention.