Changes the opacity of the cell view's $el.

When a cell is highlighted with the opacity highlighter, its $el is given the .joint-highlight-opacity class. To customize the look of this highlighted state, you can add custom CSS rules that affect this class name.

This highlighter does not currently have any options.

Example usage:

cellView.highlight(null/* defaults to cellView.el */, {
    highlighter: {
        name: 'opacity'
    }
});