title: Add rounded corners on right to Bootstrap Segmented input group
body: <p>I want to create input group with <strong>input + dropdown + button</strong></p>
  
  <p><a href="http://jsfiddle.net/eRzDq/127/" rel="nofollow">http://jsfiddle.net/eRzDq/127/</a> This is my example</p>
  
  <pre><code>&lt;div class="col-md-10"&gt;    
      &lt;h3 id="btn-groups-single"&gt;Segmented dropdown groups&lt;/h3&gt;        
      &lt;div class="input-group"&gt;
          &lt;input type="text" class="form-control " placeholder="username"/&gt;
  
        &lt;div class="input-group-btn"&gt;
            &lt;!--simple button--&gt;   
            &lt;button type="button" class="btn btn-default" data-toggle="dropdown"&gt;
                &lt;span class="caret"&gt;&lt;/span&gt;
            &lt;/button&gt;
            &lt;button type="button" class="btn btn-default"&gt;Simple&lt;/button&gt;
            &lt;!--dropdown button--&gt;    
            &lt;ul class="dropdown-menu"&gt;
                &lt;li&gt;&lt;a href="#"&gt;Dropdown link&lt;/a&gt;&lt;/li&gt;
                &lt;li&gt;&lt;a href="#"&gt;Dropdown link&lt;/a&gt;&lt;/li&gt;
            &lt;/ul&gt;
        &lt;/div&gt;      
      &lt;/div&gt;    
    &lt;/div&gt;  
  </code></pre>
  
  <p>My problem is that i don't know how to make rounded corners for Simple-Button.
  If i change order (swap simple button with dropdown button and add class <code>.dropdown-toggle</code> to dropdown) then behaviour is what i want. </p>
  
  <p>So what class i need add to simple button to make it rounded on right? (I think add class <code>.dropdown-toggle</code> to simple button is not good solution)</p>