Ubuntu – In XUbuntu there are black unreadable tabs in GTK applications such as gEdit

I'm using XFCE in Ubuntu 14.04. When I open gEdit, the tabs at the top are unreadable:

Having done some research, it appears that this is because gEdit is a GTK 2.0 application and this problem manifests itself if the theme you are using does not have specific workarounds in it for GTK 2.0 applications.

Here is what I have tried so far:

• This forum thread seems to indicate that using the Greybird theme would solve the problem. The above screenshot was taken with Greybird, and it did not solve the problem.
• This appears to be the same problem asked on StackOverflow. None of the answers are very helpful.

• This is a similar question asked here but is about tabs that are very dark but not black:

• This forum thread suggest creating a configuration file for a fallback theme for GTK 2.0 applications. Creating this configuration file did not solve my problem.