I have a Gtk 3 application and it's very unhappy with the PiX theme on my new rapbian stretch install. When I run the app from the terminal I get 81 KB of Gtk-Warnings about theme parsing. My app does NOT load it's own theme. If I run it via ssh -X from another linux box (adwaita theme ) there are no complaints.
The app used to work fine on previous raspbians. Any help would be appreciated.