gtk3 themeing metabug
Steps to Reproduce:
various problems because we pretend to use gtk3 widgets
User Profile Reset: No
User-Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:54.0) Gecko/20100101 Firefox/54.0
removing bug 121752 as its not a gtk3 themeing issue in the sense that I intended here, which is cases of use of the gtk foreign drawing api and/or theme emulation where we pretend to use gtk3 widgets.
Unfortunate outcomes on actually using native gtk3 widgets can block the GTK3 directly.