.Net Bold italik ve altı çizgili yardım

 
  void Button2Click(object sender, EventArgs e) 
  		{ 
  			 
  			if (richTextBox1.SelectionFont.Style.ToString().Contains("Bold")) 
  				richTextBox1.SelectionFont = new Font(richTextBox1.SelectionFont, richTextBox1.SelectionFont.Style & ~FontStyle.Bold); 
  			else 
  				richTextBox1.SelectionFont = new Font(richTextBox1.SelectionFont, richTextBox1.SelectionFont.Style | FontStyle.Bold); 
  		} 
  		 
  		 
  		void Button3Click(object sender, EventArgs e) 
  		{ 
  			if (richTextBox1.SelectionFont.Style.ToString().Contains("İtalic")) 
  				richTextBox1.SelectionFont = new Font(richTextBox1.SelectionFont, richTextBox1.SelectionFont.Style & ~FontStyle.Italic); 
  			else 
  				richTextBox1.SelectionFont = new Font(richTextBox1.SelectionFont, richTextBox1.SelectionFont.Style | FontStyle.Italic); 
  		}