The List example in Qt Widget Gallery supports multiple selection, but the user needs to separately activate it from the menu. This is not practical, and users need to know to look for it.
I think multiple selection should be available constantly, but having checkboxes next to each row would be ugly, so I propose a background-colored area instead. See the attachment.
Furthermore, the multiple selection mechanism could be extended to offer quick access to secondary actions. The current popup menu is uncomfortable. When a "checkbox" is activated, a toolbar could replace the top row of the list view. In my example, obvious buttons would be select all, select none, add to playlist, add to current playlist, delete.
The area outside the checkbox area would still function as it does now - single click to primary action.
