How we can write on C# in Linux: Implementing PanelApplet to Gnome Desktop

using System;
using Gnome;
using Gtk;
using Gdk;

using System.Text;
using System.Threading;
using System.Diagnostics;

using WeatherApplet.Data;
using WeatherApplet.Model;

namespace WeatherApplet.View
{
	public class PanelAppletClass :  PanelApplet
	{
		
		static Label testLabel;
		
		//Thread thread; 
		static CurrentWeather weather;

		Timer timer;
		public static void TimerTick(object state)
		{
			string country = SettingsStore.Get("state").ToString();
			string city = SettingsStore.Get("city").ToString();
			weather = WeatherService.GetWeather(country,city);
			
			testLabel.Text = String.Format ("{0}", weather.Temperature);
		}
		
		public override void Creation()
		{
			
			testLabel = new Label ("Update..");
			this.Add (testLabel);
			this.ShowAll ();
			
			//construct right-click menu
			string menuItemTemplate = "<menuitem name=\"{0}\" verb=\"{1}\" _label=\"_{2}\" pixtype=\"stock\" pixname=\"gtk-properties\"/>";
			StringBuilder menuBuilder = new StringBuilder();
			menuBuilder.Append("<popup name=\"button3\">");
			menuBuilder.AppendFormat(menuItemTemplate,"Properties","About","About");
			menuBuilder.AppendFormat(menuItemTemplate,"Properties","Preferences","Preferences");
			menuBuilder.Append("</popup>");
			
			
			
			this.SetupMenu (menuBuilder.ToString(), new BonoboUIVerb [] 
			                { 
								new BonoboUIVerb ("About", new ContextMenuItemCallback (ShowAbout)),
								new BonoboUIVerb ("Preferences", new ContextMenuItemCallback (PreferenceMenuClicked))
							}
			);
			timer = new Timer(TimerTick,null,0,5000);
		}
		
		static TreeView tv;
		void PreferenceMenuClicked()
		{
			testLabel.Text = "Build tree..";
			if(tv!=null)
					tv.Destroy();
			
			
			tv = new TreeView();
		}
		
		private void ShowAbout()
		{
			
		}

		public override string IID {
			get { 
				Debug.WriteLine("IID");
				return "OAFIID:appletSource1";
			}
		}

		public override string FactoryIID {
			get { 
				Debug.WriteLine("FactoryIID");
				return "OAFIID:appletSource1_Factory"; 
			}
		}
		
		static MyWindow w;
		protected override bool OnButtonPressEvent (EventButton evnt)
		{
			//see http://www.go-mono.com/docs/index.aspx?link=P%3AGdk.EventButton.Time
			//1 - left
			//2 - middle
			//3 - right
			if(evnt.Button == 1)
			{
				if(w!=null)
					w.Destroy();
				w = new MyWindow();
				
				if(weather!= null)			
					w.ShowWeather(weather);
			}

			return base.OnButtonPressEvent (evnt);
		}

	}
}