Change active tracing to use correct glyph instead of dot (#890)

* Change active tracing to use correct glyph instead of dot

* make the pointer on the glyph line up correctly

src/GraphControl/Control/Grapher.cpp

@@ -844,6 +844,7 @@ void Grapher::HandleTracingMovementTick(Object ^ sender, Object ^ e)
     else
     {
         ActiveTraceCursorPosition = curPos;
+        PointerValueChangedEvent(curPos);
     }
 }
 

src/GraphControl/Control/Grapher.h

@@ -20,6 +20,8 @@ public
 
 public
     delegate void TracingValueChangedEventHandler(Windows::Foundation::Point value);
+public
+    delegate void PointerValueChangedEventHandler(Windows::Foundation::Point value);
 
     [Windows::UI::Xaml::Markup::ContentPropertyAttribute(Name = L"Equations")] public ref class Grapher sealed
         : public Windows::UI::Xaml::Controls::Control,
@@ -27,6 +29,7 @@ public
     {
     public:
         event TracingValueChangedEventHandler ^ TracingValueChangedEvent;
+        event PointerValueChangedEventHandler ^ PointerValueChangedEvent;
         event TracingChangedEventHandler ^ TracingChangedEvent;
         virtual event Windows::UI::Xaml::Data::PropertyChangedEventHandler ^ PropertyChanged;