if(drawing->dotted_gc != NULL) gdk_gc_unref(drawing->dotted_gc);
if(drawing->ruler_gc_butt != NULL) gdk_gc_unref(drawing->ruler_gc_butt);
if(drawing->ruler_gc_round != NULL) gdk_gc_unref(drawing->ruler_gc_round);
if(drawing->dotted_gc != NULL) gdk_gc_unref(drawing->dotted_gc);
if(drawing->ruler_gc_butt != NULL) gdk_gc_unref(drawing->ruler_gc_butt);
if(drawing->ruler_gc_round != NULL) gdk_gc_unref(drawing->ruler_gc_round);