- /* Draw centre line.
- (bottom half) */
- cairo_move_to (cr, box_centre, bottom_whisker);
- cairo_line_to (cr, box_centre, box_bottom);
- cairo_stroke (cr);
+ /* Draw centre line. */
+ if (! isnan (bottom_whisker) && ! isnan (box_bottom))
+ {
+ /* (bottom half) */
+ cairo_move_to (cr, box_centre, bottom_whisker);
+ cairo_line_to (cr, box_centre, box_bottom);
+ cairo_stroke (cr);
+ }