How do you make this draggable on the charts?

How can I make my horizontal lines movable? ie...draggable

This is what I have right now...

//-------------------------------------------------------------------------------------------------------

using System;
using cAlgo.API;
using cAlgo.API.Indicators;

namespace cAlgo.Indicators
{
    [Indicator(IsOverlay = true, TimeZone = TimeZones.UTC)]
    public class NewIndicator : Indicator
    {
        [Parameter(DefaultValue = 0.0)]
        public double Parameter { get; set; }

        [Output("Main", PlotType = PlotType.Line)]
        public IndicatorDataSeries Result { get; set; }

       public override void Calculate(int index)
        {
            Result[index] = 1.3;
        }
    }
}

//-------------------------------------------------------------------------------------------------------

My question is this.How can I eliminate having to put in the value of the line (ie...1.3, etc...),

and make it draggable?

Thank you