alignedDropdown property
final
If true, then a DropdownButton menu's width will match the button's width.
If false (the default), then the dropdown's menu will be wider than its button. In either case the dropdown button will line up the leading edge of the menu's value with the leading edge of the values displayed by the menu items.
This property only affects DropdownButton and its menu.
Implementation
final bool alignedDropdown;