Grey Curtain in dreams
Cloth across a window — the chosen line between the inside and what may look in.
How grey changes the reading
Grey colour layers ambiguity onto the symbol. The base meaning is still there, but the dream is saying you do not yet have the colour information — the situation has not declared itself.
The base reading of Curtain
A curtain in a dream is the dream's image of a privacy you control. Curtains do not lock the world out; they decide what may be seen at which times. The dream brings the curtain when you are negotiating how much of your interior life is on view. A drawn curtain is the dream telling you the privacy is intact and is your choice. A curtain torn down or stuck open is the dream noting that the screen you thought you had — between your private life and the people watching it — is no longer functioning, and someone is seeing in.