function getLongitudeTMY3
  extends Modelica.Icons.Function;
  input String filNam "Name of weather data file" annotation(
    Dialog(loadSelector(filter = "Weather files (*.mos)", caption = "Select weather file")));
  output Modelica.SIunits.Angle lon "Longitude from the weather file";
end getLongitudeTMY3;loadSelector
for MSL compliancy as reported by @tbeu at
RWTH-EBC/AixLib#107