The ornamental design for an insert for positioning against a window pane, as shown and described.
FIG. 1 is a perspective view of an insert for positioning against a window pane showing the new design in use with a window.
FIG. 2 is a close up perspective view of the insert for positioning against a window pane of FIG. 1.
FIG. 3 is a front view of the insert for positioning against a window pane of FIG. 1.
FIG. 4 is a back view of the insert for positioning against a window pane of FIG. 1.
FIG. 5 is a right side view of the insert for positioning against a window pane of FIG. 1.
FIG. 6 is a left side view of the insert for positioning against a window pane of FIG. 1.
FIG. 7 is a top view of the insert for positioning against a window pane of FIG. 1; and,
FIG. 8 is a bottom view of the insert for positioning against a window pane of FIG. 1.
The broken lines in the drawings depict environmental subject matter only and form no part of the claimed design. The dash-dot lines in the drawings are unclaimed boundary lines and form no part of the claimed design. The subject matter between the staggered boundary lines in the drawings forms no part of the claimed design. Surface shading shows contour.