This way only certificates matching the entered text are shown initially
when the user opens the certificate list from the recipient key input
field.

GnuPG-bug-id: 5845

Add a proper button for opening the certificate selection dialog, so
that people using the keyboard can trigger this action and people
using screen readers have a chance to become aware of this action.

GnuPG-bug-id: 5845

This ensures that screen readers do not stay silent when an empty
recipient key input field gets keyboard focus.

GnuPG-bug-id: 5845

GnuPG-bug-id: 5661

This option disables the selection of public keys to use for encryption.

GnuPG-bug-id: 5661

Having them with row stretch and aligned in the center had the
effect that the widgets moved when new recipents were added. So
we just stretch the second row now to ensure that it takes up
the available space.

Check only enabled recipient widgets for valid key/group. List all
unresolved recipients in the error message.

GnuPG-bug-id: 5582

If there are no secret keys in the keyring, then disable the "sign as"
option and the "encrypt to me" option. (The latter because we currently
require a secret key for the "encrypt to me" key.)
If there are no public keys in the keyring (and therefore also no secret
keys), then disable the "encrypt for others" option and check the
"encrypt with passphrase" option which is the only possible operation in
this case.

GnuPG-bug-id: 5535

If the recipient field to remove has focus, then we move the focus to
the next recipient field or, if the field to remove is the last one, to
the previous recipient field. Since there are at least two (empty) fields,
if we remove the field, we don't have to consider the case that there are
no remaining fields.

GnuPG-bug-id: 5535

... because this may result in multiple empty recipient fields. Instead
trigger recipientsChanged() and make this check for completely empty
recipient fields instead of for fields with no key or group. There may
be non-empty recipient fields where the text doesn't match any key or
group.

GnuPG-bug-id: 5535

GnuPG-bug-id: 5535

GnuPG-bug-id: 5535

Use a separate box layout for the recipient widgets instead of fitting
them into a grid. This makes in particular the removal of widgets way
easier. Moreover, scrolling the recipient widget which has focus into
view works (almost) automatically.

GnuPG-bug-id: 5535

Decouple the update of the UI after a change of the protocol from
setting the protocol. This way we can initialize the protocol already
in-class and still setup the UI depending on the protocol without having
to rely on the uninitialized mCurrentProto being different from
GpgME::UnknownProtocol.

The initialization of mCurrentProto in-class also ensures that other
setup code uses the correct value.

GnuPG-bug-id: 5535

Set the focus policy of the scroll area to NoFocus. I think it makes no
sense to be able to give keyboard focus to the scroll area. On the
contrary, it was really confusing because neither the screen reader nor
the display gave any hint about which part of the GUI now has focus.
Took me some time and some additional debug output to figure this out.

GnuPG-bug-id: 5535

* Remove explicit setting of alignment of one of the two group boxes
  to AlignLeft which is the default anyway.
* Remove obsolete connects. encBox is not checkable anymore since a long
  time.

GnuPG-bug-id: 5535

Note: Qt automatically assigns shortcuts if one presses and holds the Alt
key, but for documentation purposes and better accessibility we explicitly
set shortcuts.

GnuPG-bug-id: 5544

GnuPG-bug-id: 5545

The key filter is superfluous since we restrict the available keys
already by setting suitable options.
Moreover, the key filter could be changed by the user overriding the
restrictions and allowing the selection of incompatible keys.

GnuPG-bug-id: 5332

... instead of relying on suitable default options (which we did not
have until now).

GnuPG-bug-id: 5332

SignEncryptWidget:
* Remove the now obsolete checks for group support

GnuPG-bug-id: 5175

This way we avoid unnecessary conversions between std::vector and QVector.

GnuPG-bug-id: 5175

This introduces a general Settings class instead of yet another
FooPreferences class.

GnuPG-bug-id: 5175

This adds the possibility to select groups of keys in the selection
dialog that can be opened when selecting recipients for encryption.

GnuPG-bug-id: 5175, 5241

This makes handling of multiple selected entries in the selection
dialog much easier, especially, once groups can also be selected in the
selection dialog.

GnuPG-bug-id: 5175, 5241

GnuPG-bug-id: 5175, 5241, 5249

The gnupg-helper was added to Libkleo some time ago.
Use it now to avoid duplicated code.

If the user enters a string in the recipient selection
line and no key can be found for that, better show an
error / warning to indicate that instead of just
ignoring that line edit.

Combined Sign & Encrypt for CMS is not implemented
in GPGSM so we disable it in the GUI to avoid a "not implemented"
error.

In notepad this makes the workflow of "decrypt and answer"
easy as the sender of a message usually encrypted the message
also to himself. So by default for an Answer you don't
have to do any key selection.

For some actions (e.g. encrypting text) we don't want
to allow mixed protocols.

This is only relevant for GpgEX as it offers explicit
sign and encrypt actions. For these actions the wizard
should be preselected accordingly.

GnuPG-Bug-Id: 3543