In this page 1, an accordion is displayed with a selected sub-item ("Sub-Item 1.2" with background color in grey).
Which is the syntax for doing this result ?
I browsed Help and forum without success...
To create sub items in Accordion you need to use this syntax, also shown by the default content when you add the widget from the palette:
To select a sub item just change the Selection property in Properties View like you normally would do for top level items. Let me know if you need more assistance.