Deprecated! It took a few years but switching between tabs is now supported out of the box (Keymap -> Other -> Tabs). You don't need this plugin anymore. Revolutionary.
The plugin adds menu actions allowing you to go to a specific tab. You can of course assign keyboard shortcuts the individual actions and for example achieve the behavior known from other editors/IDEs where you can switch between tabs with alt+<num>.
To prevent any conflicts, the plugin doesn't assign any shortcuts by itself, you need to do it manually in the Keymap (section Main menu -> Window -> Editor Tabs -> Go To Tabs).
Apache 2.0