Spanish present perfect progressive
El Pretérito Perfecto Progresivo is a tense that describes actions in progress in the past.
It uses "estar" in El Pretérito Perfecto compuesto followed by a gerund.
It is used for those actions in progress in the past with a beginning and an end in mind, which also gives the sense of a finished action.
See also: Spanish Past Tenses and All Spanish Tenses