The OnClientShowing client-side event handler is called before the RadAjaxLoadingPanel is displayed.
Two parameters are passed to the event handler with the following methods:
sender - the instance of the RadAjaxLoadingPanel client-side object.
eventArgs has the following methods:
set_cancelNativeDisplay() lets you cancel the default behaviour of theRadAjaxLoadingPanel. Calling set_cancelNativeDisplay(true) prevents the default behaviour and allows you to implement custom show animation for the loading panel.
get_loadingElement() gets the DOM element of the RadAjaxLoadingPanel.
get_updatedElement() gets the DOM element of the ajax updated control, over which the loading panel is about to be displayed.