I am using Ubuntu 14.04 with multiple desktop environments (unity, cinnamon and KDE). However, after I installed KDE, Firefox began to use oxygen GTK when I am using Unity or Cinnamon.
If a click with right button on Firefox, I get this:
I realized that others windows in firefox has the same oxygen style, like "open file". Below another screenshot.
How can I use each environment without one interfering into another one? Is it possible?