In fact here's my start at some code (attached).

If anyone fancies doing some hacking on it please help yourselves. The plan is that it runs as a stand-alone Python app and data is passed to it (and it is started if necessary) via a DBus call from mBarcode.

Which leads me onto the second point - this Python plugin is driving me mad! I've decided that it's probably easier for people to write a Python plugin to call QtDbus methods rather than making a rather complex ExternalDBusPlugin plugin for mBarcode (complex because the plugin conf file would need to contain regex expressions to determine what should be done with the barcode contents and how it should be turned into a DBus message - thinking of e.g. converting a geo:// payload to a DBus call to open a lat/lon in the wonderful Ovi Maps)

The Python plugin stuff is curious - despite stdout/stderr not supposed to be redirected, there is no output at the terminal when the plugin is loaded by mBarcode. If, however, in the __init__() method of the Python plugin class I set a redirect for the sys.stderr filehandle, I can write to a file. Very odd, and rather annoying as it then requires the class to at least be initialised before I can see any error output. I need to try setting the redirect in the main Python "workspace" before each plugin script is loaded.

I've been working through this by writing a script which runs at the command line, then trying to work out why it won't run as a plugin - curiously I see no output (which I presume indicates an error before the class is initialised) if I try to import things like PyQt4, which doesn't make me overly optimistic for the use of *Dbus imports.

Any help trying to work out what's going on appreciated as ever.