I figured out how to all-purpose-ify the image drag command.  Now with one command, it can handle multiple situations.  If you drag it:

Outside a selector/property (source.css): nothing happens

After a property (meta.property-value.css): inserts url('path/image.jpg')

Inside of empty parentheses in a property value: inserts 'path/image.jpg'

Inside of single quotes in a property value: inserts path/image.jpg

Inside a property list, outside a value: inserts a full background: shortcut tag.

Suggestions welcome.

Brett