class method

weird

    var theWindow = [[CPWindow alloc] initWithContentRect:CGRectMakeZero() styleMask:CPBorderlessBridgeWindowMask],
        contentView = [theWindow contentView];

    var bounds = [contentView bounds],
        width  = CPRectGetWidth(bounds),
        height = CPRectGetHeight(bounds);

    var buttonBar = [[CPButtonBar alloc] initWithFrame:CGRectMake(0, height - 25, width, 25)];

    [buttonBar setAutoresizingMask:CPViewWidthSizable];

    var b1 = [CPButtonBar plusButton];

    var buttons = [b1];

    [buttonBar setButtons:buttons];

    [contentView addSubview:buttonBar];

// Error:
// Uncaught CPInvalidArgumentException: + [CPButtonBar plusButton] unrecognized selector sent to class 0x000917