So far, the method listed below works for NS6, sort-of. When you right-click, the alert message will be displayed. Then...... the right context menu pops up. I tried to "return false" to cancel event bubbling which is supposed to work in Netscape 6, but is not working.
If you add your own layer and call it "context_menu", then that would display. - But then you would want to get rid of that pesky alert box.
if (document.getElementById&&!document.all)