title: C# default checked RadioButton in a GroupBox
body: <p>I have two <code>GroupBoxes</code> (groupBox1 and groupBox2) and each of which contains a set of <code>RadioButtons</code>.</p>
  
  <p>The problem is that in groupBox1, there is a default <code>RadioButton</code> (1st <code>RadioButton</code> in the group) been checked when running the project, meanwhile groupBox2 doesn't have a default checked <code>RadioButton</code>, </p>
  
  <p>I am wondering why is that and how to set a default checked <code>RadioButton</code> for groupBox2, and deselect the default <code>RadioButton</code> for groupBox1.</p>
  
  <p>ps. When I run the project, the <code>Checked</code> property of the first <code>RadioButton</code> in groupBox1 was set to 'False' though.</p>
  
  <pre><code> namespace RadioButtonsTest
  {
      partial class RadioButtonsTestForm
      {
          /// &lt;summary&gt;
          /// Required designer variable.
          /// &lt;/summary&gt;
          private System.ComponentModel.IContainer components = null;
  
          /// &lt;summary&gt;
          /// Clean up any resources being used.
          /// &lt;/summary&gt;
          /// &lt;param name="disposing"&gt;true if managed resources should be disposed; otherwise, false.&lt;/param&gt;
          protected override void Dispose(bool disposing)
          {
              if (disposing &amp;&amp; (components != null))
              {
                  components.Dispose();
              }
              base.Dispose(disposing);
          }
  
          #region Windows Form Designer generated code
  
          /// &lt;summary&gt;
          /// Required method for Designer support - do not modify
          /// the contents of this method with the code editor.
          /// &lt;/summary&gt;
          private void InitializeComponent()
          {
              this.buttonTypeGroupBox = new System.Windows.Forms.GroupBox();
              this.retryCancelButton = new System.Windows.Forms.RadioButton();
              this.yesNoRadioButton = new System.Windows.Forms.RadioButton();
              this.yesNoCancelRadioButton = new System.Windows.Forms.RadioButton();
              this.abortRetryIgnoreRadioButton = new System.Windows.Forms.RadioButton();
              this.okCancelRadioButton = new System.Windows.Forms.RadioButton();
              this.okRadioButton = new System.Windows.Forms.RadioButton();
              this.displayButton = new System.Windows.Forms.Button();
              this.iconGroupBox = new System.Windows.Forms.GroupBox();
              this.warningRadioButton = new System.Windows.Forms.RadioButton();
              this.stopRadioButton = new System.Windows.Forms.RadioButton();
              this.questionRadioButton = new System.Windows.Forms.RadioButton();
              this.informationRadioButton = new System.Windows.Forms.RadioButton();
              this.handRadioButton = new System.Windows.Forms.RadioButton();
              this.exclamationRadioButton = new System.Windows.Forms.RadioButton();
              this.errorRadioButton = new System.Windows.Forms.RadioButton();
              this.asteriskRadioButton = new System.Windows.Forms.RadioButton();
              this.displayLabel = new System.Windows.Forms.Label();
              this.buttonTypeGroupBox.SuspendLayout();
              this.iconGroupBox.SuspendLayout();
              this.SuspendLayout();
              // 
              // buttonTypeGroupBox
              // 
              this.buttonTypeGroupBox.Controls.Add(this.retryCancelButton);
              this.buttonTypeGroupBox.Controls.Add(this.yesNoRadioButton);
              this.buttonTypeGroupBox.Controls.Add(this.yesNoCancelRadioButton);
              this.buttonTypeGroupBox.Controls.Add(this.abortRetryIgnoreRadioButton);
              this.buttonTypeGroupBox.Controls.Add(this.okCancelRadioButton);
              this.buttonTypeGroupBox.Controls.Add(this.okRadioButton);
              this.buttonTypeGroupBox.Location = new System.Drawing.Point(13, 13);
              this.buttonTypeGroupBox.Name = "buttonTypeGroupBox";
              this.buttonTypeGroupBox.Size = new System.Drawing.Size(120, 160);
              this.buttonTypeGroupBox.TabIndex = 0;
              this.buttonTypeGroupBox.TabStop = false;
              this.buttonTypeGroupBox.Text = "Button Type";
              // 
              // retryCancelButton
              // 
              this.retryCancelButton.AutoSize = true;
              this.retryCancelButton.Location = new System.Drawing.Point(7, 140);
              this.retryCancelButton.Name = "retryCancelButton";
              this.retryCancelButton.Size = new System.Drawing.Size(83, 17);
              this.retryCancelButton.TabIndex = 5;
              this.retryCancelButton.TabStop = true;
              this.retryCancelButton.Text = "RetryCancel";
              this.retryCancelButton.UseVisualStyleBackColor = true;
              // 
              // yesNoRadioButton
              // 
              this.yesNoRadioButton.AutoSize = true;
              this.yesNoRadioButton.Location = new System.Drawing.Point(7, 116);
              this.yesNoRadioButton.Name = "yesNoRadioButton";
              this.yesNoRadioButton.Size = new System.Drawing.Size(57, 17);
              this.yesNoRadioButton.TabIndex = 4;
              this.yesNoRadioButton.TabStop = true;
              this.yesNoRadioButton.Text = "YesNo";
              this.yesNoRadioButton.UseVisualStyleBackColor = true;
              // 
              // yesNoCancelRadioButton
              // 
              this.yesNoCancelRadioButton.AutoSize = true;
              this.yesNoCancelRadioButton.Location = new System.Drawing.Point(7, 92);
              this.yesNoCancelRadioButton.Name = "yesNoCancelRadioButton";
              this.yesNoCancelRadioButton.Size = new System.Drawing.Size(90, 17);
              this.yesNoCancelRadioButton.TabIndex = 3;
              this.yesNoCancelRadioButton.TabStop = true;
              this.yesNoCancelRadioButton.Text = "YesNoCancel";
              this.yesNoCancelRadioButton.UseVisualStyleBackColor = true;
              // 
              // abortRetryIgnoreRadioButton
              // 
              this.abortRetryIgnoreRadioButton.AutoSize = true;
              this.abortRetryIgnoreRadioButton.Location = new System.Drawing.Point(7, 68);
              this.abortRetryIgnoreRadioButton.Name = "abortRetryIgnoreRadioButton";
              this.abortRetryIgnoreRadioButton.Size = new System.Drawing.Size(105, 17);
              this.abortRetryIgnoreRadioButton.TabIndex = 2;
              this.abortRetryIgnoreRadioButton.TabStop = true;
              this.abortRetryIgnoreRadioButton.Text = "AbortRetryIgnore";
              this.abortRetryIgnoreRadioButton.UseVisualStyleBackColor = true;
              // 
              // okCancelRadioButton
              // 
              this.okCancelRadioButton.AutoSize = true;
              this.okCancelRadioButton.Location = new System.Drawing.Point(7, 44);
              this.okCancelRadioButton.Name = "okCancelRadioButton";
              this.okCancelRadioButton.Size = new System.Drawing.Size(73, 17);
              this.okCancelRadioButton.TabIndex = 1;
              this.okCancelRadioButton.TabStop = true;
              this.okCancelRadioButton.Text = "OKCancel";
              this.okCancelRadioButton.UseVisualStyleBackColor = true;
              // 
              // okRadioButton
              // 
              this.okRadioButton.AutoSize = true;
              this.okRadioButton.Location = new System.Drawing.Point(7, 20);
              this.okRadioButton.Name = "okRadioButton";
              this.okRadioButton.Size = new System.Drawing.Size(40, 17);
              this.okRadioButton.TabIndex = 0;
              this.okRadioButton.TabStop = true;
              this.okRadioButton.Text = "OK";
              this.okRadioButton.UseVisualStyleBackColor = true;
              // 
              // displayButton
              // 
              this.displayButton.Location = new System.Drawing.Point(13, 180);
              this.displayButton.Name = "displayButton";
              this.displayButton.Size = new System.Drawing.Size(120, 40);
              this.displayButton.TabIndex = 1;
              this.displayButton.Text = "Display";
              this.displayButton.UseVisualStyleBackColor = true;
              this.displayButton.Click += new System.EventHandler(this.displayButton_Click);
              // 
              // iconGroupBox
              // 
              this.iconGroupBox.Controls.Add(this.warningRadioButton);
              this.iconGroupBox.Controls.Add(this.stopRadioButton);
              this.iconGroupBox.Controls.Add(this.questionRadioButton);
              this.iconGroupBox.Controls.Add(this.informationRadioButton);
              this.iconGroupBox.Controls.Add(this.handRadioButton);
              this.iconGroupBox.Controls.Add(this.exclamationRadioButton);
              this.iconGroupBox.Controls.Add(this.errorRadioButton);
              this.iconGroupBox.Controls.Add(this.asteriskRadioButton);
              this.iconGroupBox.Location = new System.Drawing.Point(140, 13);
              this.iconGroupBox.Name = "iconGroupBox";
              this.iconGroupBox.Size = new System.Drawing.Size(120, 207);
              this.iconGroupBox.TabIndex = 2;
              this.iconGroupBox.TabStop = false;
              this.iconGroupBox.Text = "Icon";
              // 
              // warningRadioButton
              // 
              this.warningRadioButton.AutoSize = true;
              this.warningRadioButton.Location = new System.Drawing.Point(7, 188);
              this.warningRadioButton.Name = "warningRadioButton";
              this.warningRadioButton.Size = new System.Drawing.Size(65, 17);
              this.warningRadioButton.TabIndex = 7;
              this.warningRadioButton.TabStop = true;
              this.warningRadioButton.Text = "Warning";
              this.warningRadioButton.UseVisualStyleBackColor = true;
              // 
              // stopRadioButton
              // 
              this.stopRadioButton.AutoSize = true;
              this.stopRadioButton.Location = new System.Drawing.Point(7, 164);
              this.stopRadioButton.Name = "stopRadioButton";
              this.stopRadioButton.Size = new System.Drawing.Size(47, 17);
              this.stopRadioButton.TabIndex = 6;
              this.stopRadioButton.TabStop = true;
              this.stopRadioButton.Text = "Stop";
              this.stopRadioButton.UseVisualStyleBackColor = true;
              // 
              // questionRadioButton
              // 
              this.questionRadioButton.AutoSize = true;
              this.questionRadioButton.Location = new System.Drawing.Point(7, 140);
              this.questionRadioButton.Name = "questionRadioButton";
              this.questionRadioButton.Size = new System.Drawing.Size(67, 17);
              this.questionRadioButton.TabIndex = 5;
              this.questionRadioButton.TabStop = true;
              this.questionRadioButton.Text = "Question";
              this.questionRadioButton.UseVisualStyleBackColor = true;
              // 
              // informationRadioButton
              // 
              this.informationRadioButton.AutoSize = true;
              this.informationRadioButton.Location = new System.Drawing.Point(7, 116);
              this.informationRadioButton.Name = "informationRadioButton";
              this.informationRadioButton.Size = new System.Drawing.Size(77, 17);
              this.informationRadioButton.TabIndex = 4;
              this.informationRadioButton.TabStop = true;
              this.informationRadioButton.Text = "Information";
              this.informationRadioButton.UseVisualStyleBackColor = true;
              // 
              // handRadioButton
              // 
              this.handRadioButton.AutoSize = true;
              this.handRadioButton.Location = new System.Drawing.Point(7, 92);
              this.handRadioButton.Name = "handRadioButton";
              this.handRadioButton.Size = new System.Drawing.Size(51, 17);
              this.handRadioButton.TabIndex = 3;
              this.handRadioButton.TabStop = true;
              this.handRadioButton.Text = "Hand";
              this.handRadioButton.UseVisualStyleBackColor = true;
              // 
              // exclamationRadioButton
              // 
              this.exclamationRadioButton.AutoSize = true;
              this.exclamationRadioButton.Location = new System.Drawing.Point(7, 68);
              this.exclamationRadioButton.Name = "exclamationRadioButton";
              this.exclamationRadioButton.Size = new System.Drawing.Size(82, 17);
              this.exclamationRadioButton.TabIndex = 2;
              this.exclamationRadioButton.TabStop = true;
              this.exclamationRadioButton.Text = "Exclamation";
              this.exclamationRadioButton.UseVisualStyleBackColor = true;
              // 
              // errorRadioButton
              // 
              this.errorRadioButton.AutoSize = true;
              this.errorRadioButton.Location = new System.Drawing.Point(7, 44);
              this.errorRadioButton.Name = "errorRadioButton";
              this.errorRadioButton.Size = new System.Drawing.Size(47, 17);
              this.errorRadioButton.TabIndex = 1;
              this.errorRadioButton.TabStop = true;
              this.errorRadioButton.Text = "Error";
              this.errorRadioButton.UseVisualStyleBackColor = true;
              // 
              // asteriskRadioButton
              // 
              this.asteriskRadioButton.AutoSize = true;
              this.asteriskRadioButton.Location = new System.Drawing.Point(7, 20);
              this.asteriskRadioButton.Name = "asteriskRadioButton";
              this.asteriskRadioButton.Size = new System.Drawing.Size(62, 17);
              this.asteriskRadioButton.TabIndex = 0;
              this.asteriskRadioButton.TabStop = true;
              this.asteriskRadioButton.Text = "Asterisk";
              this.asteriskRadioButton.UseVisualStyleBackColor = true;
              // 
              // displayLabel
              // 
              this.displayLabel.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
              this.displayLabel.Location = new System.Drawing.Point(13, 227);
              this.displayLabel.Name = "displayLabel";
              this.displayLabel.Size = new System.Drawing.Size(247, 15);
              this.displayLabel.TabIndex = 3;
              // 
              // RadioButtonsTestForm
              // 
              this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
              this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
              this.ClientSize = new System.Drawing.Size(284, 262);
              this.Controls.Add(this.displayLabel);
              this.Controls.Add(this.iconGroupBox);
              this.Controls.Add(this.displayButton);
              this.Controls.Add(this.buttonTypeGroupBox);
              this.Name = "RadioButtonsTestForm";
              this.Text = "Demonstrating RadioButtons";
              this.buttonTypeGroupBox.ResumeLayout(false);
              this.buttonTypeGroupBox.PerformLayout();
              this.iconGroupBox.ResumeLayout(false);
              this.iconGroupBox.PerformLayout();
              this.ResumeLayout(false);
  
          }
  
          #endregion
  
          private System.Windows.Forms.GroupBox buttonTypeGroupBox;
          private System.Windows.Forms.RadioButton retryCancelButton;
          private System.Windows.Forms.RadioButton yesNoRadioButton;
          private System.Windows.Forms.RadioButton yesNoCancelRadioButton;
          private System.Windows.Forms.RadioButton abortRetryIgnoreRadioButton;
          private System.Windows.Forms.RadioButton okCancelRadioButton;
          private System.Windows.Forms.RadioButton okRadioButton;
          private System.Windows.Forms.Button displayButton;
          private System.Windows.Forms.GroupBox iconGroupBox;
          private System.Windows.Forms.RadioButton warningRadioButton;
          private System.Windows.Forms.RadioButton stopRadioButton;
          private System.Windows.Forms.RadioButton questionRadioButton;
          private System.Windows.Forms.RadioButton informationRadioButton;
          private System.Windows.Forms.RadioButton handRadioButton;
          private System.Windows.Forms.RadioButton exclamationRadioButton;
          private System.Windows.Forms.RadioButton errorRadioButton;
          private System.Windows.Forms.RadioButton asteriskRadioButton;
          private System.Windows.Forms.Label displayLabel;
      }
  }
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/uukb2.png" alt="RadioButtons"></p>