public EveItemDropDown() { InitializeComponent(); m_ViewModel = new EveItemDropDownCompletionsModel(); DataContext = ViewModel; PART_TextBox.TextChanged += PART_TextBox_TextChanged; ViewModel.CompletionsChanged += ViewModel_CompletionsChanged; PART_CompletionList.KeyDown += PART_CompletionList_KeyDown; PART_TextBox.PreviewKeyDown += PART_TextBox_PreviewKeyDown; //LostFocus += EveItemDropDown_LostFocus; // this forces the item to be rendered - TextBoxPart will be null otherwise //Measure(new Size(Double.PositiveInfinity, Double.PositiveInfinity)); }