The event handler receives an argument of type DevExpress.XtraBars.Ribbon.Gallery.GetGalleryLoadingImageEventArgs containing data related to this event.
This event raises each time a gallery item with an asynchronously loaded image needs to be displayed. While this image is being loaded, a loading indicator is shown. Handle the GetLoadingImage event and use the e.LoadingImage property to assign your own indicator. See the OptionsImageLoad property to learn more.