\voffset=\topmargin
\advance\voffset by -1truein
\ifpdf
+ \pdfhorigin=1truein
+ \pdfvorigin=1truein
\pdfpagewidth=\pagewidth
\pdfpageheight=\pageheight
\fi
% and underlays, which are zero-size vboxes positioned absolutely in the
% front / in the back of the normal material. Also, there are global
% versions of both which are not reset after every page.
-\def\addlay#1#2{\setbox#1=\vbox{\ifvbox#1\box#1\fi\smashedvbox{#2}}}
+\def\addlay#1#2{\setbox#1=\vbox{\ifvbox#1\box#1\fi\nointerlineskip\smashedvbox{#2}}}
\def\pageunderlay{\addlay\pageunderlays}
\def\pageoverlay{\addlay\pageoverlays}
\def\commonunderlay{\addlay\commonoverlays}