Comment 9 for bug 1599453

OK, sorry for all the messages. I have a fix using CSS. Could you please make sure it doesn't break anything else? I checked the preferences screen, and am using the three profiles in this config to test.

I'm not really familiar with other widgets (like Notebook) so hopefully the changes are localized enough. At first I was using the `GtkWindow` css selector but that made the background in the preferences transparent, which was weird. So instead I added a class to windows and used that as a selector. If something that shouldn't have transparency uses the Window class from window.py then that might be an issue.

https://code.launchpad.net/~redbmk/terminator/gtk3-fix-transparency/+merge/299414