preferredSize property

@override Size get preferredSize

A size whose height depends on if the tabs have both icons and text.

AppBar uses this size to compute its own preferred size.

Implementation

@override
Size get preferredSize {
  var height = customHeight;
  if (height == null) {
    return super.preferredSize;
  } else {
    return Size.fromHeight(height + indicatorWeight);
  }
}