ChartRectangle

 using cAlgo.API;
 namespace cAlgo
 {
     // This sample shows how to use Chart.DrawRectangle method to draw a rectangle
     [Indicator(IsOverlay = true, TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
     public class ChartRectangleSample : Indicator
     {
         protected override void Initialize()
         {
             var period = Chart.LastVisibleBarIndex - Chart.FirstVisibleBarIndex;
             var rectangle = Chart.DrawRectangle("rectangle_sample", Chart.FirstVisibleBarIndex, Bars.LowPrices.Minimum(period), Chart.LastVisibleBarIndex, Bars.HighPrices.Maximum(period), Color.FromArgb(100, Color.Red));
             rectangle.IsFilled = true;
             rectangle.IsInteractive = true;
         }
         public override void Calculate(int index)
         {
         }
     }
 }

 import clr
 clr.AddReference("cAlgo.API")
 from cAlgo.API import *
 class Test():
     def initialize(self):
         period = api.Chart.LastVisibleBarIndex - api.Chart.FirstVisibleBarIndex
         rectangle = api.Chart.DrawRectangle("rectangle_sample", api.Chart.FirstVisibleBarIndex, Functions.Minimum(api.Bars.LowPrices, period), api.Chart.LastVisibleBarIndex, Functions.Maximum(api.Bars.HighPrices, period), Color.FromArgb(100, Color.Red))
         rectangle.IsFilled = True
         rectangle.IsInteractive = True