Right-click context menu for collections

When you right-click on any collection, its context menu appears:

• Create empty sub-collection: Adds a child empty collection under currently selected collection.
• Add To New Collection: Creates a new collection and move the currently selected collection into it.
• Delete Current Collection: Deletes the currently selected collection.
• Delete Hierarchy: Deletes the selected collection and its sub-items.
• Duplicate: Duplicates the currently selected collection, as well as the sub items in the collection.
• Empty Collection: Moves all sub-items out of the currently selected collection.
• Expand All List: Expands the hierarchy of the currently selected collection.
• Move to Collection: Moves the currently selected collection to another target collection.
• Merge to Collection: Merges the currently selected collection with another target collection.