WPF ComboBox DropDown part appears in the wrong place

Question

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.

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).

Answer 1

It’s a bug in WPF (not the only one, I'm afraid). It happened when I opened another window in the Loaded Event, something like:

private void Window_Loaded(object sender, RoutedEventArgs e)
{
    Window selectionWindow = new SelectionWindow();
    bool? result = selectionWindow.ShowDialog();
    if (result == true)
        RecordChanged();
}

I already found a workabout.