Add comments for messages extracted from .desktop files

I agree and I propose this is done for other files as well. GtkBuilder examples: "This is a button label", "This is an action tooltip" et cetera.

No need to start each comment with "Translators:" though.

xml2po already does that in a succint way:

#. When image changes, this message will be marked fuzzy or untranslated for you.
#. It doesn't matter what you translate it to: it's not used at all.
#: C/accerciser.xml:461(None)
msgid "@@image: 'figures/script_recorder.png'; md5=a15027c852c58df789886f6aadf0130c"
msgstr ""

#: C/accerciser.xml:24(title)
msgid "<application>Accerciser</application> Manual v0.2.0"
msgstr ""

#: C/accerciser.xml:27(year)
msgid "2006"
msgstr ""

Notice that in a specific situation a more verbose comment was added. This could apply also for strftime-formated messages, or messages with placeholders in general, as well as messages with old-style or new-style context.

I guess we can reuse the format xml2po uses in the source reference where it puts tag in parenthesis. I wouldn't like to add a long comment, but I would like to support comments added by maintainers to .desktop.in file.

Any progress?

FWIW as of http://bazaar.launchpad.net/~intltool/intltool/trunk/revision/601 (way old) one can already at least put custom comments in .desktop files that will be visible by translators.

This said, yeah it could come in handy to show the key if no other comment was specified, and it'd be easy enough with an else around those lines:

sub type_ini {
    ### For generic translatable desktop files ###
    while ($input =~ /^(#(.+)\n)?^_([A-Za-z0-9\-]+)\s*=\s*(.*)$/mg) {
        if (defined($2)) {
            $comments{$4} = $2;
        } else {
            $comments{$4} = "key '$3'"
        }
        add_message($4);
    }
}

(e.g. capture the key in the regex, and use it as comment if none is provided)

The current regex only matches a single line of comment above the key, which lead to workarounds like https://git.gnome.org/browse/gnome-control-center/commit/?id=5c10ce45b8f2902e71a36649b9d0a31ccff6dc0f and very long lines in source text. Will you change it to match multiple lines?