Microsoft.Windows.Controls.Ribbon.RibbonComboBox.OnApplyTemplate C# (CSharp) Method

        public override void OnApplyTemplate()
        {
            CoerceValue(ControlSizeDefinitionProperty);
            base.OnApplyTemplate();

            EditableTextBoxSite = GetTemplateChild(EditableTextBoxTemplateName) as TextBox;

            // EditableTextBoxSite should have been set by now if it's in the visual tree
            if (EditableTextBoxSite != null)
            {
                EditableTextBoxSite.TextChanged += new TextChangedEventHandler(OnEditableTextBoxTextChanged);
                EditableTextBoxSite.SelectionChanged += new RoutedEventHandler(OnEditableTextBoxSelectionChanged);
            }

            // At startup ComboBox needs SelectedItem from its first RibbonGallery in order to populate its TextBox.
            // RibbonGallery needs to be hooked up to the Visual tree, so that its DataContext is inherited.
            // Similarly RibbonGalleryCategory and RibbonGalleryItem should be in Visual tree to extract SelectedItem and the container for the SelectedItem
            // Therefore its not sufficient to just generate containers, we need a full Layout on RibbonGallery.
            if (Popup != null && Popup.Child != null)
            {
                Popup.Child.Measure(new Size());
                UpdateFirstGallery();
            }
        }