UpdateCount keeps track of whether the named Variants list is in the middle of an update operation (an operation that makes several changes to the list). Every time the application calls BeginUpdate, the value of UpdateCount is incremented. Every call to EndUpdate decrements the value of UpdateCount.  

When UpdateCount changes from 0 to 1, and when it changes from 1 to 0, TAbstractNamedVariants calls the SetUpdateState method. This allows TAbstractNamedVariants descendants to respond in some way (such as enabling or suppressing repaints of a control that displays the values in the list) when an update operation begins or ends. 

BeginUpdate 

EndUpdate 

SetUpdateState