I watched the

CodePudding user response：

When the DropdownButton is on focused, it uses focusColor. For the long press it uses the splashColor. Yo can wrap with Theme and provide splashColor.

Theme(
  data: ThemeData(
    splashColor: Colors.green,
  ),
  child: DropdownButton<String>(
    dropdownColor: Colors.pink, // main bg 
    focusColor: Colors.amber,// when focused
    value: dropdownValue,