So actually WaitForControlExists is a call to public WaitForControlPropertyEqual, something like:
return this.WaitForControlPropertyEqual(UITestControl.PropertyNames.Exists, true, timeout);
Instead, your assistant may call:
public bool WaitForControlPropertyNotEqual(string propertyName,
object propertyValue, int millisecondsTimeout)
In addition, as Kek points out, there is a public WaitForControlNotExist method.
, , , ( ):
public static bool WaitForCondition<T>(T conditionContext, Predicate<T> conditionEvaluator, int millisecondsTimeout)
Thread.Sleep , , .