title: Form without focus/activation
body: <p>I want to implement intellisense-like feature for my multiline textbox. The intellisense control is placed in standard form without control box (so, no title or maximize/minimze bottons are visible).</p>
  
  <p>All works fine, but if intellisense-form is shown and user clicks into the intellisense form, the main form lost focus (so, user must click back into textbox for writing).</p>
  
  <p>I know <code>ShowWithoutActivation</code> property, but it works only on activation, not on "standard focus".</p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>I found the help on <a href="http://www.daniweb.com/software-development/csharp/threads/273724" rel="nofollow">http://www.daniweb.com/software-development/csharp/threads/273724</a> , but the presented code does not work. It throws "Invalid parameter" exception during "Show()" method.</p>