You opening a curtain, or shutters, on a window symbolizes you feeling the need to 'see something'. The unseen one in your dream is your subconscious not wanting you to see that 'something'.
Meaning...your subconscious is warning you not to go where you don't belong. To stay away from something that doesn't concern you, lest your emotional, or physical self, be hurt.
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Did you over-hear something about somebody, or something, and you're just aching to tell someone?
Did someone ask you to go somewhere, or do something, that could be dangerous, harmful, or illegal?
Do you feel your curiosity getting the better of you about someone, or a situation, and you're thinking about 'snooping', or 'peeking', just a little?


Hope this helps. Good Luck!