Press This in 4.9

In WordPress 4.9, Press This has found a new home as a “canonical” plugin.

Proposed in #41689 and committed in r41584, Press This and the supporting functions are no longer in Core at all. This is notably different than the Link Manager deprecation, which left all of the code in Core but deactivated behind a filter. If you are extending the WP_Press_This class, you will need to update your plugin or theme as it is no longer present in Core.

When someone visits wp-admin/press-this.php, they are given a prompt to install the new plugin or to notify their administrator to install it:

If installing it through the prompt above, the activation flow will return them to Press This:

If you are extending Press This or are depending on functionality from it, you can see how to check for plugin availability via 4.9’s wp-admin/press-this.php and please comment on #37938 discussing if some of the parsing functionality of Press This would be beneficial ported back into Core.

In the new plugin, older bookmarklets will no longer function and this feature is discontinued. Usage of bookmarklets across the web has decreased significantly and bad actors attempting to trick users to preform unsavory actions increased over the years. Coupled with advancing toward a new editing in experience in Core, we decided it was a suitable time to make these changes in one swift move.

Continued development of Press This will happen at https://github.com/WordPress/press-this/ and I hope those who like the streamline editing experience will continue to contribute. Short-term goals include switching to the REST API instead of admin-ajax and tweaking the current experience.

#4-9, #dev-notes