[lmi] Supplemental report column selection

[Greg Chicares]

The GUI for selecting supplemental reports:
  File | Preferences
  "View" tab
could be easier to use. At present, selecting ten columns requires
pulling down a combobox ten times, and each time selecting from a
list of four or five dozen choices (the same list each time).

I think a single wxCheckListBox might be an improvement: then we'd
have just one list with dozens of choices, and end users could
pick up to twelve just by checking boxes.

Column order matters greatly for supplemental reports, so we'd have
to provide a way to sort the listbox items. In the 'widgets' sample,
I see a wxEditableListBox example that has a user-sortable order,
but what we want is the UserSortable and Checkable properties in one
control, without the Editable property. I'm guessing that the up and
down arrows to change the order are a wxRearrangeCtrl embedded in
wxEditableListBox, so maybe what I'm envisioning is a wxCheckListBox
with a wxRearrangeCtrl to manage the order of its items. It isn't
indispensable to integrate them into a single control, but we really
would need this to work in wxXRC.

Vadim, if I've expressed the idea clearly enough, can you tell me
what specific controls we'd use to accomplish this? I don't find a
wxRearrangeCtrl in any of the wx samples. This image search:
  https://www.google.com/search?q=wxRearrangeCtrl&tbm=isch
finds inheritance diagrams but no screenshot of the actual control.
Going by the doxygen documentation, I'd guess that wxRearrangeCtrl
is what I'm looking for: it consists of up and down buttons, along
with a wxRearrangeList, which derives from wxCheckListBox. However,
if I try to use it in XRC, as a control within a panel, I get:

  XRC error:
  no handler found for XML node "object" (class "wxRearrangeCtrl")

If I try using it in place of a wxPanel (because it derives
from wxPanel), I get the error message above plus:

  notebookpage child must be a window

And if I try using a wxRearrangeList directly, instead of wxListBox:

  no handler found for XML node "object" (class "wxRearrangeList")

Should all built-in wx controls have XRC handlers built into wx?
I could write handlers in lmi (like "InputSequenceEntryXmlHandler",
which is obviously specific to lmi), but I'd rather avoid doing
that if such handlers really belong in wx and were just overlooked.

Once we've chosen the right control and implemented it (or chosen
a handful, experimented with them, and picked the best one), there's
another step:
  http://savannah.nongnu.org/support/?105590
  Save and retrieve supplemental reports
because the improvements mentioned above merely make less tedious
to pick a set of columns, but in practice there are a few sets that
get used over and over again, and picking a file that embodies one
of those sets is much easier than selecting each of its elements
repeatedly.

And then there's another step:
  http://savannah.nongnu.org/support/?105589
  Allow multiple supplemental reports
which (like anything else) is a daunting task as long as we're
using XSL templates, but becomes tractable when we generate PDF
files in a less hideous way.