crash on exit.

[Gediminas Paulauskas <menesis delfi lt>]

Today I found some state, when balsa constantly crashed on exit. Then
tracked down to almost exact place where it crashes, but still did't
understand.

in src/main.c (balsa_exit) it closes all local mailboxes, then enters empty_trash function.

there is a call to
libbalsa_mailbox_open(balsa_app.trash, FALSE);

and it does not return. gdb says "received a SIGSEGV in gtk_type_check_object_cast"

But then I deleted something, closed Balsa, and this error is gone! Though I
was able to repruducing it every time, if just start, open mailboxes, but
deleted anything. So, it does no more crash, but says a similar message:

Gtk-WARNING **: invalid cast from `GtkAttachOptions' to `GtkCTree'

or, more often, just

Gtk-WARNING **: invalid cast from `(unknown)' to `GtkCTree'

So I think there shoul be a conflict with with LIBBALSA_TYPE_MAILBOX, though
everything seems to be correct. So, if someone could look into it carefully,
maybe will see more than I.

Also, there are two identical functions: malbox_empty_trash() in
main-window.c and empty_trash() in main.c. There should be only one...

-- 
Gediminas Paulauskas