CGSize ContentSizeForFrame(CGSize size, bool hbar, bool vbar) { var hbarPtr = hbar ? classScroller_Handle : IntPtr.Zero; var vbarPtr = vbar ? classScroller_Handle : IntPtr.Zero; // 10.7+, use Xamarin.Mac api when it supports null scroller class parameters return(Messaging.CGSize_objc_msgSend_CGSize_IntPtr_IntPtr_UInt64_UInt64_Int64(Control.ClassHandle, selContentSizeForFrameSize_HorizontalScrollerClass_VerticalScrollerClass_BorderType_ControlSize_ScrollerStyle_Handle, size, hbarPtr, vbarPtr, (ulong)Control.BorderType, (ulong)Control.VerticalScroller.ControlSize, (long)Control.VerticalScroller.ScrollerStyle)); }