Why Carana, she was a precocious child by all accounts and singularly very determined? She had easy access to the window by climbing onto the bed. She had been wakening and crying since the Tuesday night so by Thursday she had probably had enough.
Precocious, yes, but she was still not quite 4 years old.
A little girl, exhausted by all the fun activities, not just on the day, but during the whole week. Apparently sound asleep when the parents left.
If they had left her during the day, while she was still full of energy, then I wouldn't have excluded tugging on the shutter strap to play Tarzan or anything else that I might have done at her age. If I had done that, the first consequence would have been that I'd have jammed the strap.
Setting that aside...
I have never come across a 3-4-year-old who would willingly climb out of a dark window late at night. Nor can I think of one who would close heavy verandah sliding doors, plus gates behind her. Nor one who would think to put on sandals, or leave without Cuddle-Cat.
A precocious / enterprising 5-7 year-old might have done, but she was an exhausted 3-year-old, going on 4.