title: Combobox closes automatically
body: <p>I have restyled my combobox's template so that the drop down popup appears at the origin of the combobox. Here's how it's done:</p>
  
  <pre><code>&lt;ControlTemplate TargetType="{x:Type ComboBox}"&gt;
   &lt;Grid&gt;
    &lt;ToggleButton/&gt;
    &lt;ContentPresenter/&gt;
    &lt;Popup PlacementRectangle="0,0,0,0" &gt;
     &lt;Grid Name="DropDown"&gt;
      ...
     &lt;/Grid&gt;
    &lt;/Popup&gt;
   &lt;/Grid&gt;
  &lt;/ControlTemplate&gt;
  </code></pre>
  
  <p>The only problem I have with this is that when I click on the combobox it automatically selects the item the mouse is over and closes. The only way I can select any other item is by holding the mouse button and then moving the mouse over the wanted item. How to fix this?</p>