Comment 92 for bug 365300

I met with the same problem on my Ubuntu 13.04 laptop. I'd like to post a partial/possible solution here in case that someone want to try.

Here is the problem.
    Inside Google Chrome, sometimes when you right click (for only once) on a web page, it will behave like you double right clicked and as a result it navigate back. (`Back` is the first menu item on the context menu).

When does the problem occur.
    It happens that the problem does not occur with Ubuntu 13.04's built-in themes: Ambiance, Highconstrast, Radiance. When I installed and activated third-party themes like Uncomplicated, Flatsutdio, Mediterraneanlight, etc the problem does occur.

The possible cause of the problem.
    https://bugzilla.gnome.org/show_bug.cgi?id=591258

The solution.
    After hours search and research, I found why the built-in themes won't be affected. In these themes, a little padding is added to the top of menus. When you right click on the padding, it won't activate the first menu item. That's it. So we can add that to other theme by simply adding (or modifying) GtkMenu ::vertical-padding = 3 to <PathOfTheTheme>/gtk-2.0/gtkrc, under `style "default"` section. You could refer to /usr/share/themes/Ambiance/gtk-2.0/gtkrc.

Hope it helps.