I did update my GUI-library Geeonx and the designer tool GeeonxCreator. Now it works with Linux x86 64 bit, MacOS x86 64 bit and SDL 2.
For those who do not know my library: The library provides window management, drawing and update of all GUI-elements like windows, pulldown-menus, icons, inputforms and buttons of an application.
Take a look at www.geeonx.org for further information.
MacOS versions are only tested on my MacMini with MacOS X 10.6.8. So beta testing for other MacOS versions are welcome.