Do not draw appendix lines below en of document

This bug is pretty old, but it was not visible because the grey area
below the document would overwrite it.

It would be better to close the frame at the end of the document, but
this is for later.

src/RowPainter.cpp

@@ -314,7 +314,7 @@ void RowPainter::paintAppendix() const
 		y += 2 * defaultRowHeight();
 
 	pi_.pain.line(1, y, 1, yo_ + row_.height(), Color_appendix);
-	pi_.pain.line(tm_.width() - 2, y, tm_.width() - 2, yo_ + row_.height(), Color_appendix);
+	pi_.pain.line(tm_.width() - 2, y, tm_.width() - 2, yo_ + row_.descent(), Color_appendix);
 }