Currently in RadAccordion one accordion item is always expanded.  I would need the option the accordion to be fully collapsed. In addition, when the header of an expanded item is clicked, it should be collapsed.

the issue could be reproduced when RadListView or RadDataGrid controls are inside the content of the accordion item

In the Accordion the control there is an option to allow collapse all. I also see the option to set which item is expanded by default. However I would like to have all features opened by default. I think it would be an easy addition to be added to the control and this would give another option for flexibility when it comes to laying out how the UI interacts with the consumer.

when you want to set corner radius to RadBorder, the Accordion Background is visible behind the border

When IsVisible property of an AccordionItem is set to "false", it is hidden, but an empty space with the height of the item header is left.

provide an option for setting a CornerRadius to RadAccordionItem