Csharp/C Sharp/Event/System Event

Get Event sender in event handler

 
using System;
using System.Drawing;
using System.Windows.Forms;
   
class TwoButtons: Form
{
     readonly Button btnLarger, btnSmaller;
     readonly int    cxBtn, cyBtn, dxBtn;
   
     public static void Main()
     {
          Application.Run(new TwoButtons());
     }
     public TwoButtons()
     {
          ResizeRedraw = true;
   
          cxBtn = 200;
          cyBtn = 100;
          dxBtn = 12;
   
          btnLarger = new Button();
          btnLarger.Parent = this;
          btnLarger.Text   = "&Larger";
          btnLarger.Size   = new Size(cxBtn, cyBtn);
          btnLarger.Click += new EventHandler(ButtonOnClick);
   
          btnSmaller = new Button();
          btnSmaller.Parent = this;
          btnSmaller.Text   = "&Smaller";
          btnSmaller.Size   = new Size(cxBtn, cyBtn);
          btnSmaller.Click += new EventHandler(ButtonOnClick);
   
          OnResize(EventArgs.Empty);
     }
     protected override void OnResize(EventArgs ea)
     {
          base.OnResize(ea);
   
          btnLarger.Location =
                         new Point(ClientSize.Width / 2 - cxBtn - dxBtn / 2,
                                  (ClientSize.Height - cyBtn) / 2);
          btnSmaller.Location =
                         new Point(ClientSize.Width / 2 + dxBtn / 2,
                                  (ClientSize.Height - cyBtn) / 2);
     }
     void ButtonOnClick(object obj, EventArgs ea)
     {
          Button btn = (Button) obj;
   
          if (btn == btnLarger)
          {
               Left   -= (int)(0.1 * Width);
               Top    -= (int)(0.1 * Height);
               Width  += (int)(0.1 * Width);
               Height += (int)(0.1 * Height);
          }
          else
          {
               Left   += (int)(Width  / 22f);
               Top    += (int)(Height / 22f);
               Width  -= (int)(Width  / 11f);
               Height -= (int)(Height / 11f);
          }
     }
}

System Events: User Preference Changed

using System;
using System.Collections.Generic;
using System.ruponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using Microsoft.Win32;
public class Form1 : Form
{
    private System.Windows.Forms.Label label2;
    
  public Form1() {
        this.Font = SystemFonts.IconTitleFont;
        this.AutoScaleDimensions = new System.Drawing.SizeF(6.0F, 13.0F);
        InitializeComponent();
        SystemEvents.UserPreferenceChanged += new UserPreferenceChangedEventHandler(SystemEvents_UserPreferenceChanged);
  }
    private void SystemEvents_UserPreferenceChanged(object sender, UserPreferenceChangedEventArgs e)
    {
        if (e.Category == UserPreferenceCategory.Window)
        {
            this.Font = SystemFonts.IconTitleFont;
        }
    }
    private void InitializeComponent()
    {
        this.label2 = new System.Windows.Forms.Label();
        this.SuspendLayout();
        // 
        // label2
        // 
        this.label2.Location = new System.Drawing.Point(12, 9);
        this.label2.Name = "label2";
        this.label2.Size = new System.Drawing.Size(220, 55);
        this.label2.TabIndex = 2;
        this.label2.Text = "Try changing the Small Fonts/Large Fonts setting for th" +
            "e computer.";
        // 
        // Form1
        // 
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.ClientSize = new System.Drawing.Size(244, 138);
        this.Controls.Add(this.label2);
        this.Text = "Form1";
        this.ResumeLayout(false);
    }
  [STAThread]
  static void Main()
  {
    Application.EnableVisualStyles();
    Application.Run(new Form1());
  }
}