Our UI Framework is constantly growing and improving. And as a plugin author, the last thing you want is to scramble to fix a library of custom plugins after a new Framework release has unintended side-effects.
That's why we've introduced Framework versioning. Private Plugins are now tied to a specific Framework release that won't change until you want it to. The version can be upgraded or downgraded at any time.
Plugin authors are encouraged to upgrade Framework at their convenience. Framework releases contain bug fixes, new features, and support for an ever-growing pool of screens and devices.
If your middle name happens to be "Danger", select "Always track latest", which means your plugin will always use the newest, bleeding-edge Framework release the moment it's published.