/usr/lib/libgtkglext-x11-1.0.so.0 is in libgtkglext1 1.2.0-3.1fakesync3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/libgtkglext-x11-1.0.so.0.0.0
/usr/lib/libgtkglext-x11-1.0.so.0.0.0