[lmi] Grid-bases census view editor UI questions

[Vadim Zeitlin]

 Hello,

 Trying to implement a wxGrid-based UI for the census view editor, I've
realized that I'm not really sure how is it supposed to work, from the user
point of view. The main question I have is about selection: in the current
UI, the selection unit is a row, and at least one (but possibly more) row
is always selected. However I'm not sure if the census behaves like this
because this is what we really need or because this is all that the
currently used control supports and, in particular, because the currently
used wxDataViewCtrl doesn't really have any notion of the "cursor cell",
it's always part of the "currently selected row".

 By contrast, wxGrid does always have the current cell. Additionally,
wxGrid selection handling is quite flexible and by default allows all of
row, column, cell and rectangular blocks selections (and all of them can be
combined by using Ctrl/Shift keys when extending the selection). I don't
really see why would we need individual cell or block selection (but please
correct me if I'm wrong), but could it perhaps be useful to allow column
selection, in addition to row selection? Of course, for this to be really
useful, we'd have to have some operations that can be usefully applied to
the columns. AFAIR from the previous discussions almost 10 years ago, you
did want to allow users to operate on columns, but currently we don't see
to have any such operations (which is, of course, a Catch-22 problem
because we can't define them with the current UI).

 OTOH, partially because of this flexibility, we can't guarantee that there
is always non-empty selection in wxGrid. How important is it to always have
some selection? And if it is, should we just consider the row containing
the current cell as the "active" row in absence of the selection? This is
what I wanted to do initially, but then I thought about the situation in
which the current cell wouldn't be part of the selection and couldn't
decide what should be done in this case. Perhaps we should try to reproduce
the current UI behaviour and ensure that there is "real" selection
available at all time and that it always includes the current cell? This
should be doable (although I'm not 100% sure about this), but considering
that we wanted to move away from wxDataViewCtrl row-centric behaviour,
might not be what we actually want to do.


 Please let me know how should the selection behave, if possible, because
I'm really not sure about what we're trying to achieve here. Moreover, I
have more UI questions, but they depend on the selection handling, so I'd
like to have an answer to this one before asking the other ones (I just
hope that the perspective of getting even more emails won't demotivate you
from answering!).

 Thanks in advance,
VZ

pgp02fMTVy0rr.pgp
Description: PGP signature