Hi @Francival, 

On a quick look at Leaflet's documentation, I've found the tooltip functionality that allows among other things to fulfill this exact use case.

You can have two scenarios:

1. Using Shapes\Circle block:
   
   On the Map's block Initialized event handler add the following JS node:
   

   let circleShape = OutSystems.Maps.MapAPI.ShapeManager.GetShapeById($parameters.ShapeId);
   
   circleShape.provider.bindTooltip( "This is a circle shape!", {
       permanent: false,  // It will only show when hovering
       direction: "top"
   });
   
   
   // $parameters.ShapeId being the identifier of the Shapes\Circle block 
   		

   
   
   
2. Using drawn circles (drawing tools):
   
   On the Map's block Initialize event handler add the following JS node:

   let shapes = OutSystems.Maps.MapAPI.MapManager.GetMapById($parameters.MapId).shapes;
   let circles = shapes.filter(shape => shape._type === "Circle");
   
   // Iterate over the filtered circles and bind a tooltip to each one
   circles.forEach(circleObj => {
           circleObj.provider.bindTooltip( "This is a circle shape from drawing tools!", {
           permanent: false,  // It will only show when hovering
           direction: "top"
       });
   });
   
   
   // $parameters.MapId being the identifier of the Map block  
                   

   Note: you can also use similar logic to apply on the event OnDrawingChange so you get this once you finish drawing the circle

Here's the result:

Hope it helps!

Cheers,
GM