Hi!
In 7.0 there were many more reasons to create a single-state dynamic panel than there are now that groups exist.
For example, if you want to move multiple objects with a single move command, in 7.0 dynamic panels were your only option: now you can do that with a group. Or you want both the icon and the the rectangle of a button to simultaneously react when moused over: you can now set “Trigger Mouse Interaction Styles” to True on a group (and also have the group handle OnClick).
Groups are easier to edit, since you just click into them, AND you can edit them in the context of their surroundings. That said, here are remaining reasons to use a single-state dynamic panel:
[ul]
[li]A dynamic panel is the only thing you can drag[/li][li]Dynamic panels can scroll; you can’t create a scrolling region in a page with a group[/li][li]Push-pull widgets is confined to the boundaries of a dynamic panel, so you’d use one to limit the scope of push-pull to an area on the page. Push/pull of objects in a group pushes/pulls objects outside of the group as well (which has its own situational advantages)[/li][li]A dynamic panel has its own coordinate system, whereas a group uses the page’s coordinate system. When you are using Move commands on items in a dynamic panel, panel.x and panel.y don’t change; moving an object in a group can change the group’s (x,y) location on the page, so group.x and group.y don’t provide a reliable basis relative placement of the group’s objects.[/li][/ul]