Library /sys$common/syshlp/examples/decw/custom.hlb Overview, auto_shadow  *Conan The Librarian (sorry for the slow response - running on an old VAX)

               The default value of the Automatic shadowing toggle button
               can be set using the Custom.autoShadow resource in the
               CUSTOM.DAT file as follows:

               Custom.autoShadowing: False

               The default value is True.