AZ SlideIn has some CSS that you can find here: 
slidein.css
                            
                            
                            A CSS class is added to 
AZSlideIn when the 
AZSlideIn is active.
                            
                            
                            <div class="az-slidein az-slidein-active"></div>
                            
                            This allows you to check if an 
AZSlideIn is active or deactivated, (open/closed).
                            
                            
                            
1. new AZSlideIn();
                            
                            $.subscribeonce("functionlib/azSlideInReady", function (e, data)
                            {
                                data.$SlideIn.hasClass("az-slidein-active")
                            });
                            
                            
2. var AZSlideIn = new AZSlideIn();
                            
                            AZSlideIn.$SlideIn.hasClass("az-slidein-active")