Whoa! "beta testing by Lord Libidan" I only just saw that. Wicked!
Anyways, it works well, there are a few things I would possibly implement though.
Firstly, I put in an image with a white background, and seeing where the 10 block marks are is quite hard. Is there any way you could either get it to auto check the background for a dark/light colour, or add an option to the possible interface so you could select one of a few colours.
Secondly, white. You just implemented B5200, but most people prefer BLANC. I know my local store has like 1000 BLANCs, but only 10 B5200. Reason being the B5200 is bleached, and so reacts to sunlight badly, going brown. Possible selection on the interface to include B5200? Not sure how else you could deal with it apart from removing B5200... I think some online pattern makers remove B5200...
Thirdly, closing it is an issue. I think this might be due to you using python, but I'm not sure.
You currently have to close it using your dock and not the top bar of the program.
Fourthly, could you make it so once the post script file has been closed it auto-deletes? Or somehow make it so the .ps saves as a pdf then deletes? Once the .ps is made its pretty useless, you have to save it as a pdf for any use. I don't know if its possible though, unless the .ps is opened and converted into a pdf in the spriter program itself. I think I'm understanding that correctly?
Otherwise, its coming along nicely. So nicely in fact that since 0.2 I haven't used another program. Oh! I know what I was going to say! If you're adding an interface for size variation, a suggestion would be to specify pixels and actual measurements based on count sizes. So you could specify count 14 at 10cm, and it would do the calculation for you. And then you could put into into the end page saying how big the pattern will be, even if they only specified the pixels.
Thought of two more things...
KG chart and other pattern makers state how many cells there are in the pattern. Something I never use, but noticed you didn't have. Maybe see who else uses them, and possibly put them in. No point putting things in when people don't use them though, is there?
I was talking to someone the other day IRL about spriter and they said they used anchor threads (They were english like me). Not sure if it really calls for adding another set of colours, but I said I would tell you what they said.
Is it me or is spriter sounding more and more like KG Chart and less like a simple drag and drop?