title: GDI+ HotKeyPrefix only on Alt key
body: <p>I use the following code in custom button to draw the text inside an overridden <code>OnPaint</code> event:</p>
  
  <pre class="lang-cs prettyprint-override"><code>// ...
  Point TextPoint = new Point(2, 2);
  StringFormat format = new StringFormat();
  format.HotkeyPrefix = System.Drawing.Text.HotkeyPrefix.Show;
  e.Graphics.DrawString(this.Text, this.Font, new SolidBrush(this.ForeColor), TextPoint, format);
  // ...
  </code></pre>
  
  <p>This works fine and even respects the <code>&amp;</code> hotkey. However, the underline that is normally shown underneath the hotkey (e.g <code>C&amp;ancel</code> would become <code>Ca̲ncel</code>), which is normally only shown when the user presses the <kbd>Alt</kbd> key, is now always shown.<br>
  <strong>Is there any way I can render this underline only when the user presses <kbd>Alt</kbd> like on the default .NET button (<code>System.Windows.Forms.Button</code>)?</strong></p>