I just ran into the exact same error message trying to install "gresolver":
"libgail18 : Depends: libgtk2.0-0 (= 2.24.30-1ubuntu1) but 2.24.30-1ubuntu1.16.04.1 is to be installed"
When I enable "xenial-updates main" the dependency error disappears and I can install the required libgtk packages.
My distro is Xubuntu 16.04.3.
I just ran into the exact same error message trying to install "gresolver":
"libgail18 : Depends: libgtk2.0-0 (= 2.24.30-1ubuntu1) but 2.24.30- 1ubuntu1. 16.04.1 is to be installed"
When I enable "xenial-updates main" the dependency error disappears and I can install the required libgtk packages.
My distro is Xubuntu 16.04.3.