how to highlight all the edges in the graph?

[ucrkarthik]

When the page first loads, all the edges on the page are highlighted. Once any part of the page is clicked, the highlighted edges disappear. When a node is clicked, the nodes edges gets highlighted. how can I toggle the edges so it gets highlighted/unhighlighted when clicking the white space. The reset function unhighlights the edges. Is there a function to highlight all the edges again?