textStyle property
The style to use for the message of the tooltip.
If null, the message's TextStyle will be determined based on
ThemeData. If ThemeData.brightness is set to Brightness.dark,
ThemeData.textTheme.body1 will be used with Colors.white. Otherwise,
if ThemeData.brightness is set to Brightness.light,
ThemeData.textTheme.body1 will be used with Colors.black.
Implementation
final TextStyle? textStyle;