ok, trying to add your plugin, and am getting an odd behavior.
It appears to have patched properly (I used the latest stable release and used your patch). The only thing I had to do was remove the two entries to create the png images, because somehow, those weren't working.
But, the real issue, is that now when I go to use the "Filters" tab, nothing gets triggered, meaning nothing happens. I can click around on the Identities and Folders tabs, but the Filters tab simply doesn't work.
I noticed the URL that gets created from those tabs, and changed the URL to point to ?_task=settings&_action=sieverules and it did go to your sive filter page...
Does anyone have any idea as to why the tab isn't clicking??? Is it not enabled?
Thanks,
Tim.