Controls trigger activation and deactivation (focus/blur) events
obj.onControlActivating = function(event){...};
obj.onControlActivated = function(event){...};
obj.onControlDeactivating = function(event){...};
obj.onControlDeactivated = function(event){...};
event (object) - DOM event
obj.onControlActivated = function(event){
alert(this.getControlText());
}
If you cancel (return non-zero value) onControlDeactivating
event - the focus wil stay in the control.