[DGH] inks needs to be reset to addMin; sometimes inks is disabled

[Bernard Devlin]

When I use DGH to add a custom control to a datagrid (e.g. just a
'classic' field control), I can get my custom field to display the
data when the datagrid is updated.  However, the datagrid for that
column(s) loses the alternating row colour that is found in other
columns.

In my experiments with solving this, I found that reseting the 'inks'
to addMin in DGH would reintroduce the alternating rows. But sometimes
even the 'inks' menu is disabled.

Any clues as to what is going on?  I expect this is a little
off-the-beaten-track for the DGH, which is why no-one else has run
into this problem.

Bernard