dropdown_button2-v3.0.0-beta.0

• BREAKING: Replaces DropdownMenuItem with DropdownItem to provide extra functionality.

  Instead of:

  items: items.map((String item) => DropdownMenuItem<String>(...)).toList(),

  do:

  items: items.map((String item) => DropdownItem<String>(...)).toList(),

• Add closeOnTap property to DropdownItem. It controls whether the dropdown should close when the item is tapped.

• BREAKING: Support setting different heights for items.

  Instead of:

  items: items
    .map((String item) => DropdownItem<String>(
        value: item,
        child: Text(item),
      ))
    .toList(),
  menuItemStyleData: const MenuItemStyleData(
    height: 40,
  ),

  do:

  items: items
    .map((String item) => DropdownItem<String>(
          value: item,
          height: 40,
          child: Text(item),
        ))
    .toList(),

• Support adding separator widget internally, closes #134.

• Update highlight behavior, closes #184.