Cocoa binding to NSButton messes with enabled state

When an NSButton's value and hidden state are bound to properties, changing either property enables the button.

See example code:

@interface MyClass ()


@property (nonatomic) BOOL buttonHidden;
@property (nonatomic) BOOL buttonState;


@end



@implementation MyClass {
	__weak IBOutlet NSButton *button;  // The button is in a view designed in IB
}


- (void)awakeFromNib {
	[super awakeFromNib];
	[button bind:NSHiddenBinding toObject:self withKeyPath:@"buttonHidden" options:nil];
	[button bind:NSValueBinding toObject:self withKeyPath:@"buttonState" options:nil];
	button.enabled = NO;
	self.buttonHidden = NO;   // This enables the button. If this line isn't executed, the buttons stays disabled. 
}

@end

Note that the issue occurs only of both properties are bound.

I wonder if this is by design or a bug.