var instance = new Vintasoft.Imaging.Annotation.UI.Panels.WebUiAnnotationListPanelJS(settings, stateButton);

var value; // Type: function
value = instance.get_CreateCollectionHeaderContentCallback();

function get_CreateCollectionHeaderContentCallback() : Function;

A function, which returns UI elements for the header of annotation collection in annotation list panel, OR "null".
Here is function prototype "function __createAnnotationCollectionHeaderContent(annotationCollection, index)", where "annotationCollection" parameter is an instance of WebAnnotationViewCollectionJS type, index - zero-based index of annotation collection. Important: "__createAnnotationCollectionHeaderContent" function must return not empty array of WebUiElementJS objects.