Currently, it can be dynamic as well when setting the key prop of the PannelBar to the same value of the expanded property, as this will re-initialize it when the expanded state changes.
Also, if the requirement is to make them all expanded initially, this can be done by looping over all items and setting their expanded property to true.
Regards,
Stefan
Progress Telerik
Progress is here for your business, like always. Read more about the measures we are taking to ensure business continuity and help fight the COVID-19 pandemic. Our thoughts here at Progress are with those affected by the outbreak.