After updating a multisite installation to WP 3.8, when in the My Sites Dashboard, hovering over "Themes" or "Plugins", no submenu pops out. There are however submenus popping out of "Sites", "Users", and "Settings".
I found advice elsewhere to disable plugins one by one, and make sure a standard theme is being used. However, with a multisite installation I suppose there is no way to make sure a standard theme is being used (unless all sites are changed to that theme).
Any ideas how to understand and fix this situation? Is there anywhere to locate an error message?
I should mention that one of the sites is using a private plugin that I wrote, but it does not seem to have any problems as far as I can tell.