UILabels don't have an onChange event. What are you referring to?
UILabel inherits UIWidget.
UIWidget has OnChange.
When UILabel changes dimensions of its UIRect(because of resize freely) the event OnChange is not triggered.
But, when UILabel is set to shrink content and when i manually change the dimensions of UILabel - OnChange event is triggered properly.
This is inconsistent behaviour because in both cases UIRect dimensions are changed but only in one case the event is triggered.