Eskil

    foreach i [array names ::Pref] {
        # Skip unchanged options.
        if {[info exists ::DefaultPref($i)]} {
            if {$::DefaultPref($i) eq $::Pref($i)} {
                continue
            }
            puts $ch "# $i default : $::DefaultPref($i)"
        }
        puts $ch [list set ::Pref($i) $::Pref($i)]
    }
    close $ch

    tk_messageBox -icon info -title "Saved" -message \
            "Preferences saved to:\n[file nativename $rcfile]"