Visual cue for filter

.. by highlighting chart title too if a filter is
   being applied.

This is important to warn users that the data being plotted
is adjusted to the search/filter (either globally or in the
chart settings).

src/TreeMapWindow.cpp

@@ -237,6 +237,7 @@ TreeMapWindow::refresh()
 
         refreshPlot();
     }
+    repaint(); // get title repainted
 }
 
 void