Could you describe to us in more details what exactly you mean by not working as the built in dialogs. The RadWindow's predefined dialogs are a lot different then the built-in dialogs from the framework.
Could give us more details on what features that are included in the framework built-in dialogs you find useful and in what scenarios? This would help us see if implementing such functionalities would be beneficial and in what scenarios.
Thank you for your feedback.
the Telerik team