As far as I understood from your explanations, the RadWindow autosizes fine when it is initially opened. After that you change the size of the content and the RadWindow stays the same size. This is the correct behavior by design - the RadWindow automatically autosizes when it is opened. To make it autosize again explicitly, you should call its method autoSize when you change the content size. The autoSize method is documented below:
and you can make the make the RadWindow autosize itself with an animation or not, controlling that with an input parameter.
In addition, you can see this in action in our online demo below:
When you open the RadWindow and you show the calendar dropdown, the RadWindow autosizes itself. When the calendar dropdown is hidden, the window autosize back to the changed size.
Please, examine the provided resources and use the suggested approach. In case you still experience problem, please share sample demo page - there is no need to show your actual content, just put the same elements and logic - e.g DIV, random strings, etc since the content information, databases, etc itself is not what matters in the case but the layout configuration.
the Telerik team
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