Largo2

I use a extension class specifically for markers. I can't remember where I found it , Was on google somewhere. I did look again but couldn't find the author. I take no credit for this class & if anyone knows who created it please let me know so I can credit them.
 
 

First of all you would create a new class named say Marker.cs.
Put the code in that spoiler in there and rename to your namespace (where it says YourProjectName).
Then from that point in a callout you can use Marker1 = new Marker(); With your parameters.
Marker1.Visible = true;