Menu suggestions welcome

I would like to build the menu illustrated below.

O – o – o – OO

Each big O (button) contains a submenu (small o:s) of variable length.
When initialized, the first O’s submenu will be visible and the others collpased.
When an O is clicked its submenu will be expanded and the others collapse.
I would like the whole menu to be built from an xml file and preferringly there should be some animation when submenus are expanded/collapsed.

If you have seen a pre-built menu component of this kind somewhere, I would be glad for a link (could cost …)

thanks!