The dialogs of the RadEditor are RadWindow instances, therefore, you can interact with them as plain RadWindow controls. This KB article-Custom loading sign for RadWindow
, shows how to hide the loading icon.
As for the tool, this demo-Custom Tools
, demonstrates how to customize the tool's icon.
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.