In map views, the view inside a container (the 'viewport') reflects the container's current scroll position. So, dragging the background of the interior of a container scrolls the inside of that container and also updates the opening co-ordinates of the child map opened via that viewport ($MapScrollX and $MapScrollY). Adornments seen on a viewport map cannot be dragged.
Conversely, scrolling in a map view of the children will result in scrolling of the parent container's viewport contents.
Note that dragging a note in a container viewport outside the viewport drags that note out of the container (i.e. promotes it from child to sibling). To drag the container icon on the map, drag its title bar.