Dear Maintainer,
Having the Debian Unstable repository available (even with a low priority) causes
libxcb-xinput-dev to be installable, but leaves the older libxcb1-dev from Debian
Stable. This results in compilation errors from any app that attempts to #include
the xinput headers, due to a version incompatibility.
The solution is to uninstall libxcb-xinput-dev, or to migrate far more packages
to the newer version (including upgrading libc).
The problem appears to be a simple packaging issue, where the dependency is shown
as simply "libxcb1-dev" with no version information attached. If it declared that
it required libxcb1-dev version 1.13.1-2, this would inform apt correctly.