postinst is in hime-gtk2-immodule 0.9.10+git20170427+dfsg1-2build4.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | #!/bin/sh
set -e
set -u
GTK_QUERY_IMMODULES=/usr/lib/x86_64-linux-gnu/libgtk2.0-0/gtk-query-immodules-2.0
if [ -x $GTK_QUERY_IMMODULES ]; then
    case "$1" in
        configure)
            $GTK_QUERY_IMMODULES --update-cache
            ;;
    esac
else
    echo "Cannot find $GTK_QUERY_IMMODULES" >&2
fi
exit 0
 |