- The preview is not scaled
- No color dialogs
- The filterCase field is not set
The first issue is the most critical and also the hardest to fix as GIMP does not seem to allow a copy of the current layer to be scaled in memory without being added to the image.
Although the plugin could make it work after checking the host signature by treating it like Photoshop 2.5 and scaling the preview itself.
The second issue is relatively easy to fix, the most difficult part would be the color space conversion but that may not be very widely used.
The third issue is a few lines to fix.
I hope it helps.