I was looking around the folders code and discovered a minor bug.  If
you create a folder with a dot in it (like test.box) RC will display a
folder called test with a box sub-folder.  That is all as it should be.
 The problem is that it allows you to drag and drop messages into the
phantom folder and displays it as if it were a real folder.  When you
drag into the folder the message appears to go away, and of course
doesn't appear in the phantom folder.  When you refresh the folder that
you dragged the message from the message reappears (which is good - at
least it isn't lost forever).  What should happen is that the phantom
folder should be greyed out, and undraggable (and probably unselectable).

When you query IMAP for the folder list, it helpfully tags that folder
as Noselect, but we don't do anything with that tag, or for that matter
with any other tags (including such useful ones as HasChildren and
HasNoChildren).  I propose rewriting the folder getting routines to pass
all of the tags through to the roundcube "layer" so that we can decide
what to do about the presentation of these folders.

This requires the modification of
iil_C_ListSubscribed in lib/imap.inc as well as _list_mailboxes and
list_mailboxes in rcube_imap, and the various functions that call those
functions (about 6 or so).  So my question is does anyone have any
reservations about me going ahead with this, and does anyone anticipate
any cross IMAP server problems?

-Charles