Please see the official release notes for list of new features and improvements. And also the blog post about Mendix 9
https://www.mendix.com/blog/mendix-9-0-where-it-all-comes-together/
https://docs.mendix.com/releasenotes/studio-pro/9.0
Some stuff did also change between 9.0 and the latest version (currently 9.6). If you go to https://marketplace.mendix.com/link/studiopro/ you will always find the latest release notes.
In 9.6 Ctrl-tab works!