Changing window state causes visual glitches
After changing window state from normal to maximized double border appears around a path-bar. Switching to another window, then switching back to nautilus fixes the issue.
Changing window state from maximized to normal creates opposite issue - no edge border on path-bar buttons. Switching windows also fixes the issue.
Tested on Fedora 30 with nautilus 3.31.90 and flatpak from gnome-apps-nightly repo (NautilusDevel).