El Condicional Perfecto Progresivo

Conditional Perfect Progressive

The Spanish Perfect Conditional tense can also be progressive and express hypothetical situations that may have been happening in the past, seen as continuous possible actions: "something that would have (not) been happening". For example: 

Yo habría estado saltando de alegría si eso me hubiera pasado a mí.
I would have been bursting with joy if that had happened to me. 

Si yo fuera él, habría estado planeando mi huida.
If I were him, I would have been planning my escape.

¿Qué habrían estado haciendo esos chicos tan tarde en la calle?
 [I wonder] what would those boys have been doing outside so late [at night]?

Let me take a look at that...