Hi Ang,
Greetings from the Syncfusion team. We have gone over your scenario and prepared a sample for you to use as a guide, please feel free to use it. We use a separate Text widget to set the custom text, and we get the point index of the tapped section using onPointTapped, and we set the text if the index is different, and the empty text if the index is the same.
Thanks,
Dharanitharan. P