All objects (images, sounds,... ) added on a page, as well as handwritten annotations and highlights, can be selected with the cursor and grouped to become a single object, by clicking the "Group" icon in the toolbar.
They can also be ungrouped by clicking again on the icon "Ungroup".
There are two ways to perform a multiple selection :
the cursor enables to select a set of objects that are in the rectangle chosen if the objects are contiguous.
it is also possible to use Shift+Click to group non-contiguous objects.