Real Studio creates the Old School Carbon applications, but has beta support for Cocoa applications. Just for fun, I compiled one of my apps for Cocoa, since Real Studio's Cocoa support is getting a lot more robust. Wow. Lots of weird things happened to the user interface. The Log window that's a drawer turned into a separate window. The same system fonts now have different spacing, so text doesn't fit very well and things got ugly. I could spend a lot of time on each app tweaking the user interface to make the Cocoa version look just like the Carbon version, but I'm no longer happy with the look of these apps anyway. Apple has been modernizing the look of apps for a while now, so if and when I go back to making any changes, a radical user interface change will be required.
Looking at Apple Mail as an example, I like the sidebar look which I would probably use for the Log in a future version instead of a drawer. Similarly, the separate window that I now use for a Skills browser would probably move into the main window.
Looking at Apple Mail as an example, I like the sidebar look which I would probably use for the Log in a future version instead of a drawer. Similarly, the separate window that I now use for a Skills browser would probably move into the main window.

As mentioned in my previous post, I've started thinking about a character editor. I'm going to try to do this one in Cocoa right from the beginning. Stealing ideas from Apple Mail, the photo shows my early user interface ideas.
Note the disclosure triangles used to select different sections and characters within that section.
Note the handle at the bottom right of the sidebar which resizes the width of the sidebar. The window itself will also be resizeable.
Note the background and text colors which make the whole thing look more modern.
I should probably look at Apple's Lion apps before I go much further, since Apple will be changing things some more. Stay tuned.
Note the disclosure triangles used to select different sections and characters within that section.
Note the handle at the bottom right of the sidebar which resizes the width of the sidebar. The window itself will also be resizeable.
Note the background and text colors which make the whole thing look more modern.
I should probably look at Apple's Lion apps before I go much further, since Apple will be changing things some more. Stay tuned.