So I elected to buy a Canon Selphy ES-30 which is a compact dye sublimation photo printer that can also print gold and silver foil. It was listed as having Macintosh support, which is good because I don't do windows. It's a cute little thing, and takes its printing supplies as little cartridges that contain both the paper and the dye sub ink sheets. This makes it easy to switch between different media, and ensures that the ink and paper stay in synch and are compatible. They're specialized enough that they'll only ever be available from Canon, and they're not particularly cheap. But that's fine, it's cost effective for my occasional use.
But then it turns out that the Macintosh support is only partial - you can print color or black and white, but no gold or silver foil. It is my opinion that if you claim to "support" a computer for a product, that you support all the product's capabilities. Otherwise, it's partial support at best, and this should be stated clearly in all sales literature. Otherwise, you are lying to me, and I do not appreciate being lied to.
I waited a while to see if there would be an update that would add foil support, but none was forthcoming. Then I wrote Canon and asked if they would send me the protocol, so I could implement this myself.
They refused, saying the information was proprietary. What? Why? You're not selling printer drivers, you're selling printers, or more to the point, you're selling printer supplies. The more people who can use your printers, the more printers and supplies you will sell. Keeping the protocol a secret is nonsense. I offered to sign an NDA, but no reply at all. I realize that companies avoid giving out technical information because it might lead to more support questions. I explained that I would not ask for further support, nor use the information in a way that would cause this to happen.
Do you know what would have happened, if you had furnished the interface specification? I would have extended the existing Gutenprint Canon Selphy support to include the ES-30, including its metal foil printing capabilities. I would have provided my changes back to the Gutenprint project for inclusion in their core software. This would have given Canon ES-30 support to Linux and BSD users, and since Apple uses Gutenprint to provide their third-party printer drivers, you would have gotten Macintosh support for free. Better yet, customer support for this driver would have come from the Gutenprint project and Apple — saving you support money. I would have written a positive review of the printer, and all my adoring readers would have gone out and bought them. The underserved Macintosh, Linux, and BSD communities would have bought the now-supported printer, and supplies for it. As the cartridges are not easy to replicate (unlike refilling inkjet cartridges), you would have had a solid revenue stream for years to come, that no one could take away from you. You would have enjoyed a positive mindshare in a large, geeky customer base - and their friends, families, and employers.
But no. You decided to take the low road, keep things secret for no reason, and now you're stuck with unpreferred vendor status. I'll buy my cameræ from Nikon, Fuji, and Olympus. I'll buy my printers from Epson and HP. And I'll tell all my friends how you refused to play nice.