Hi John,
Thank you for contacting Syncfusion Support
The SelectionChanging event of an TabNavigationControl will trigger when clicking the left and right button of a navigation button and also while the item was changed using TabStrip. The same has been demonstrated in our sample. Please download it from the following location:
Sample:
TabNavigation_120490Please try our solution and let us know if it helps you.
Regards,
Vijayalakshmi V.R.