title: How can I show dynamic markers in DevExpress XtraCharts?
body: <p>I am using the DevExpress.XtraCharts.SwiftPlotDiagram to show a diagram in my WinForms c# application.</p>
  
  <p>I would like to show a dynamic marker on the series' line, kind of like you have in Google Finance: a simple dot or circle on the line that follows your mouse movement on the series' line. </p>
  
  <p>It appears to me that DevExpress does not support it. It only allows you to add static markers. </p>
  
  <p>So I was looking for ways of doing it myself. One idea was to simply put an image on top of the series that I move along with the X position of the mouse. This works fine for rectangular shaped markers but not for round shaped markers as it seems that DevExpress does not draw transparant pixels in the image actually transparant. They automatically get the background color of the chart. Does anyone know the reason why it doesn't draw those pixels transparantly or have another idea on how to implement a dynamic marker?</p>