Comment 5 for bug 1598295

Okay, so — in short — the problem was that the command `/usr/lib/x86_64-linux-gnu/libgtk-3-0/gtk-query-immodules-3.0 --update-cache` wasn't run upon distro upgrade. Actually, I'm not sure if it's a distro bug or not, because in my case the distro-upgrade came not quite fine. I was having a PPA with latest GCC, which I didn't purge — that looks right, why would I care if I'm using a binary distro anyway? However, after upgrade Xorg didn't even start; long story short — libstdc++, for some reason, didn't have some function which some apps were using. Reinstalling to vanilla libstdc++ solved the problem. I did even see a bug about it somewhere, but can't find it. But I can assume that some apps for distro upgrade failed to run because of the library — as the bug with $GTK_IM_MODULE not the only problem I encountered here. I'm seeing things like missing tray icons, ignored preview options in Dolphin, crashing vlc, and more.