Two of the apps I use most for writing are Bear and Ulysses. They are beautifully designed and built applications, and offer lots of features that I find very useful. In general terms I use Bear for holding notes on areas that I am interested in and, in some cases, researching. Recently I had occasion to want to connect a note in Bear to a sheet (effectively a document) in Ulysses. A quick bit of research on the Web revealed that Ulysses implements the x-callback protocol, that was originally developed to allow iOS applications to talk to each other in the very heavily sandboxed environment that is iOS. I was working on my MacBook Pro at the time, so wanted to link a Bear note on MacOS Sierra to a Ulysses sheet in that same environment. Happily it worked seamlessly, and I was very happy to be able to jump from my Bear note to the Ulysses sheet quickly and easily. Not only that, the link is preserved in the iOS environment, where I have both applications installed so that I can work on either my MBP, my iPhone or iPad. O res mirabile the links are preserved in that environment too. Now that’s what I call design.