ColorThemeChangeEventArgs

 using cAlgo.API;
 namespace cAlgo
 {
     // This example shows how to use the Chart ColorThemeChangeEventArgs
     [Indicator(IsOverlay = true, TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
     public class ColorThemeChangeEventArgsSample : Indicator
     {
         protected override void Initialize()
         {
             Application.ColorThemeChanged += Application_ColorThemeChanged;
         }
         private void Application_ColorThemeChanged(ColorThemeChangeEventArgs obj)
         {
             var text = string.Format("Theme Changed To: {0}", obj.ColorTheme);
             Chart.DrawStaticText("text", text, VerticalAlignment.Top, HorizontalAlignment.Right, Color.Red);
         }
         public override void Calculate(int index)
         {
         }
     }
 }

 import clr
 clr.AddReference("cAlgo.API")
 from cAlgo.API import *
 class Test():    
     def initialize(self):
         api.Application.ColorThemeChanged += self.on_application_color_theme_changed
     def on_application_color_theme_changed(self, args):
         api.Chart.DrawStaticText("text", f"Theme Changed To: {args.ColorTheme}", VerticalAlignment.Top, HorizontalAlignment.Right, Color.Red)