Broken tab navigation in popup with WPF user control hosted inside Winforms in default AppDomain
问题 I have a WPF user control that uses a Popup. This control is a plugin and can be loaded in the main AppDomain or in a separate AppDomain, and it is hosted in a Winforms form using ElementHost. When the plugin is loaded in the main AppDomain, and the popup is opened, tabbing between the fields of the popup instead moves focus to the first control of the popup windows parent. When it is loaded in a new AppDomain, the tab behavior works as expected/desired (it cycles through the controls in the