Appears to be due to recent changes (more recent than the last bugs I filed as it compiled fine after fixing those).  Anyway, I'm getting:

printunixdialog.cc: In member function `void Gtk::PrintUnixDialog::add_custom_ta
b(const Gtk::Widget&, const Glib::ustring&)':
printunixdialog.cc:47: error: invalid use of undefined type `struct Gtk::Label'
../../gtk/gtkmm/container.h:53: error: forward declaration of `struct Gtk::Label
'
printunixdialog.cc:48: error: no matching function for call to `Gtk::PrintUnixDi
alog::add_custom_tab(const Gtk::Widget&, Gtk::Label&)'
printunixdialog.cc:46: note: candidates are: void Gtk::PrintUnixDialog::add_custom_tab(const Gtk::Widget&, const Glib::ustring&)
../../gtk/gtkmm/printunixdialog.h:132: note:                 void Gtk::PrintUnixDialog::add_custom_tab(const Gtk::Widget&, const Gtk::Widget&)
make[5]: *** [printunixdialog.lo] Error 1