public GroupTreeSizeChangedEventArg(SpaceSize oldSize, SpaceSize newSize, GroupTreeSizeChangedEnum action)
{
OldSize = oldSize;
NewSize = newSize;
Action = action;
}
void OnChangedSizeEvent(SpaceSize oldSize, SpaceSize newSize,
GroupTreeSizeChangedEnum action)
{
ChangedSizeEvent?.Invoke(this,
new GroupTreeSizeChangedEventArg(oldSize, newSize, action));
}