title: Property or indexer 'Font.Bold' can not be assigned to - it is read only
body: <p>I would like it to form a tool change it at one of the characters in thickness (Bold), or underscore (Underline) during program run.
  I tried to set the next program code, but failed. I received the following error: "Property or indexer 'Font.Bold' can not be assigned to - it is read only"</p>
  
  <p>Why can not I set this property?</p>
  
  <pre><code>((TextBox)tabControl1.Controls[S].Controls[K]).Font.Bold = true;
  </code></pre>