DropdownMenuDecorationBuilder typedef
The type of builder function used by DropdownMenu.decorationBuilder to build the InputDecoration passed to the inner text field.
The context is the context that the decoration is being built in.
The controller is the MenuController that can be used to open and close
the menu with and query the current state.
Implementation
typedef DropdownMenuDecorationBuilder =
InputDecoration Function(BuildContext context, MenuController controller);