src/Tools/jEdit/src/pretty_tooltip.scala

       val formatted = Pretty.formatted(info.info, margin, metric)
       val lines =
         XML.traverse_text(formatted)(0)(
           (n: Int, s: String) => n + s.iterator.filter(_ == '\n').length)
 
-      val h = painter.getFontMetrics.getHeight * (lines + 1) + geometry.deco_height
+      val h = painter.getLineHeight * (lines + 1) + geometry.deco_height
       val margin1 =
         if (h <= h_max)
           (0.0 /: split_lines(XML.content(formatted)))({ case (m, line) => m max metric(line) })
         else margin
       val w = (metric.unit * (margin1 + metric.average)).round.toInt + geometry.deco_width