setFirstFocus method

void setFirstFocus (FocusScopeNode child)

Makes the given child the first focus of this scope.

If the child has another parent scope, the child is first removed from that scope. After this method returns isFirstFocus will be true for the child.

Implementation 

void setFirstFocus(FocusScopeNode child) {
  assert(child != null);
  assert(child._parent == null || child._parent == this);
  if (_firstChild == child)
    return;
  child.detach();
  _prepend(child);
  assert(child._parent == this);
  _didChangeFocusChain();
}