[Behavior] Tabbing [Not supported] Not applicable. [Supported] 
Tab order for hosted Windows Forms controls is the same as when those controls are hosted in a Windows Forms-based application. Tabbing from a WPF control to a Windows Forms control with the TAB key and SHIFT+TAB keys works as usual. Windows Forms controls that have a TabStop property value of false do not receive focus when the user tabs through controls. Each WindowsFormsHost control has a TabIndex value, which determines when that WindowsFormsHost control will receive focus. Windows Forms controls that are contained inside a WindowsFormsHost container follow the order specified by the TabIndex property. Tabbing from the last tab index puts focus on the next WPF control, if one exists. If no other focusable WPF control exists, tabbing returns to the first Windows Forms control in the tab order. TabIndex values for controls inside the WindowsFormsHost are relative to sibling Windows Forms controls that are contained in the WindowsFormsHost control. Tabbing honors control-specific behavior. For example, pressing the TAB key in a TextBox control that has a AcceptsTab property value of true enters a tab in the text box instead of moving the focus.