This menu appears when you right-click an item's icon in the panel.
Open. Open the item with the default opener.
Delete from uDock. Remove the item from the panel.
Show in Finder. Reveal the item in Finder window.
Get info. Display item info window.
Quick look. Preview the item.
Set custom icon. Allows you to assign any image to the selected item. Choose a picture file from the open window. The picture will be assigned to the item.