require that an edit cell be defined. This stops a lot of commands
from failing on non-writeable cells. There really should not be a
concept of "non-editable" cells at all, just non-writeable ones.
and HOME substitution in filenames needs to watch for a NULL
cd_file, and (2) The routine that removes the (UNNAMED) cell when
another cell is loaded needs to NULL the boxRootDef pointer or else
it ends up pointing to deallocated memory.
routine was erasing and redrawing in one step, which ignored the
possibility of having to erase from one window and redraw in
another if the cursor moved focus from one window to another.
This led to crosshairs being improperly drawn and erased when
multiple windows were present, if the windows had different cells
loaded.
rescaling the internal units. The former in particular can
cause problems when moving the root box and importing cells from
a script (same change as made to magic-8.1).
Tim Edwards