+ (NSColor *) staticColour {
    __strong static NSColor* _sharedInstance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _sharedInstance = [NSColor colorWithCalibratedRed:255.f green:255.f blue:255.f alpha:1.0];
    });
    return _sharedInstance;
}