MarkerTitle := 'should be bold';
Map.OpenMarkerInfoWindowHtml(IdMarker,'Not bold <b>'+ MarkerTitle + '<br />'+
'Lat : ' + floattostr(latitude)+ '<br />' +
'Lon : '+ floattostr(longitude) + '</b><br />');
As you can see MarkerTitle ie 'should be bold' does not render in bold.
Thanks
Lee