This puts the graphical/display options with the other similar options
in that dialog, rather than with the dimension options found in the Set
Grid dialog, which is in the Dimensions menu.
Also place the option itself in the GAL Display Options structure, so it
can be updated using the observer mechanism there.
The setter for the style in the GAL interface is removed, as the public
interface for setting this option is now to modify the
GAL_DISPLAY_OPTIONS structure and notify the GAL when done.