[apps/regression] In graph view, display a specific legend when the mean

dot is selected

Change-Id: Ib55101435c1205709ea5a17616e7daa09ae388bc

apps/regression/data.cpp

@@ -103,6 +103,10 @@ int Data::moveCursorHorizontally(int direction) {
   return windowHasMoved;
 }
 
+int Data::selectedDotIndex() {
+  return m_selectedDotIndex;
+}
+
 /* Window */
 
 void Data::setDefault() {