preferBelow property
final
Whether the tooltip defaults to being displayed below the widget.
If there is insufficient space to display the tooltip in the preferred direction, the tooltip will be displayed in the opposite direction.
If this property is null, then TooltipThemeData.preferBelow is used. If that is also null, the default value is true.
Applying TooltipThemeData.preferBelow: false for the entire app
is recommended to avoid having a finger or cursor hide a tooltip.
Implementation
final bool? preferBelow;