title: WPF ComboBox DropDown part appears in the wrong place
body: <p>I put several ComboBoxes on a XAML window. When I expand any of them, the DropDown part appears on the upper left corner of the screen.</p>
  
  <p>I use Visual Studio 2008 C# Express. I don't remember this phenomenon when I used Visual Studio 2008 (Trial Version), though I use the same FrameWork (3.5).</p>