same as title, any have solution..?
Adding RadEditor to the RadPrompt template is not possible with the current implementation of the WindowManager. In general, you can only use plain HTML in the Dialog templates, server controls are not supported and may even result in errors. More information about the WindowManager's dialogs and their specifics can be found here:https://docs.telerik.com/devtools/aspnet-ajax/controls/window/alert,-confirm,-prompt-dialogs/how-to-change-the-dialog-templates
You can create a more complex dialog, containing server-side controls by using a standard RadWindow: