Fix LTM title filter color bug

.. the title of an LTM chart doesn't change when you
   select or deselect a filter in the sidebar.

src/LTMWindow.cpp

@@ -339,6 +339,8 @@ LTMWindow::filterChanged()
     }
 
     refreshPlot();
+
+    repaint(); // just for the title..
 }
 
 void