...and I cannot understand how to remove the border and rounded corner around the items.
I succeded with the expandable part, where I now have the same color and no border. But between the reduced item and its expanded part (see row 5) remains a line. How to remove it?
The Divider Height is, of course, the space between Items.
You don't want borders around the title (I finally get it? ); to achieve this, you must set the border thickness of the Panel containing the lblTitle, that is the pnlTitle, to 0.