void TextSelectionOverlayChanged(InputValue value, Rect caretRect)

Signature for reporting changes to the selection component of an InputValue for the purposes of a TextSelectionOverlay. The caretRect argument gives the location of the caret in the coordinate space of the RenderBox given by the TextSelectionOverlay.renderObject.

Used by TextSelectionOverlay.onSelectionOverlayChanged.

Source 

typedef void TextSelectionOverlayChanged(InputValue value, Rect caretRect);