fixedSize property Null safety
final
The button's size.
This size is still constrained by the style's minimumSize and maximumSize. Fixed size dimensions whose value is double.infinity are ignored.
To specify buttons with a fixed width and the default height use
fixedSize: Size.fromWidth(320). Similarly, to specify a fixed
height and the default width use fixedSize: Size.fromHeight(100).
Implementation
final MaterialStateProperty<Size?>? fixedSize;