Reproduce

1. Start app, then click the notify icon to show context menu.
2. Change theme at runtime ThemeManager.Current.ApplicationTheme = XXX.
3. Click the notify icon to show context menu, its theme not change.

Environment (please complete the following information):

• .net: 5
• IDE vs2019
• Version HandyControls 3.1.1

Additional context
Add any other context about the problem here.