Whe right clicking in windows that have popup menus you can hold mouse button, wait until popup appears and release above the desired item to click it. This is different from Windows that have popup appear only on mouse release. And it leads to accident menu item clicking sometimes. Looks like the issue is there: https://bugs.launchpad.net/ubuntu/+bug/320259, https://bugzilla.gnome.org/show_bug.cgi?id=575071.
Is there's any way to change popup appearance time at least?