Might be interested in a shot of the PS plugin that inspired MultiTile - Xaos Terrazzo - it does make excellent seamless tiles. (tried it with shellout/xnview also pspi - no good)
Maybe something for the Gmic experts to consider
That linux plugin is so slow, effectively useless. 20 secs for the drop down menu, another 20 secs for the option to apply. But then minutes if you try and drag the selection, and much longer to render. Lack of any indication of working is a big drawback. Quite heavy on CPU usage, I saw 30% (3GHz 2-core). In linux, I got results by setting it going, moving to another desktop and forgetting about it.
Looking in my archives, I have a Windows Gimp 1.2 + GTK 1.3 so I must have used it sometime, but nothing in the way of scripts/plugins.