"Save As" always saves everything and, when the save is done, makes the

"Save As" always saves everything and, when the save is done, makes the
new file the current file, as is the case in most if not all other GUI
applications.

A new "Export Specified Packets" menu option allows you to specify which
packets to write out, with the default being the displayed packets (and
those on which the displayed packets depend for, e.g.  reassembly), and
never makes the resulting file the current file.

The two operations are conceptually distinct.  Lumping them into one
menu item, with the default for "Save As" being "displayed packets only"
and thus making it behave like the latter operation, was causing some
confusion; see, for example, bug 6640.

Make the dialog popped up if you try to "Save As" or "Export Specified
Packets" on top of an existing file ask the "do you want to do this?"
question in the main part of the message, and note in the secondary text
that doing that will overwrite what's in the file; that matches what
TextEdit on OS X and the GNOME text editor say.

svn path=/trunk/; revision=42792