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# NSWindowDidChangeBackingPropertiesNotification User Info Properties

Constants that represent values in the user info dictionary of the `didChangeBackingPropertiesNotification` notification.

## Topics

### Constants

[`class let oldScaleFactorUserInfoKey: String`](/documentation/AppKit/NSWindow/oldScaleFactorUserInfoKey)

An NSNumber containing the old scale factor.

[`class let oldColorSpaceUserInfoKey: String`](/documentation/AppKit/NSWindow/oldColorSpaceUserInfoKey)

An [`NSColorSpace`](/documentation/AppKit/NSColorSpace) instance containing the old colorspace.


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