Window Manager is Stuck due to a Missing Symbol
I use xfce4-wm-4.14.5 on FreeBSD 12.1. Today, the WN got stuck but did not crash because of the missing symbol "FcWeightFromOpenTypeDouble". I got the following message when I tried to start Firefox from the fallback window manager:
libpangoft2-1.0.so.0 undefined symbol FcWeightFromOpenTypeDouble
Upgrading "fontconfig" has solved the problem, but I believe that in such cases XFCE4 should crash with an error message.