In early February we reported that the Widget Customizer plugin had received the green light to be merged into the WordPress core for 3.9. At that time Andrew Nacin opened a ticket to help precipitate any necessary improvements and guide the details of how the files should be merged.
After three weeks of polishing, the Widget Customizer feature was officially merged into core today. Props go out to Weston Ruter and his team of dedicated developers who helped make this feature a reality.
For those adventurous souls who have been testing the feature using the Widget Customizer plugin, you can now remove it and start testing it within the trunk.
No Changes Required From Theme Developers
Theme developers will not need to add theme support for the customizer to indicate a widget’s support for live previews, as this was stripped from the version of the plugin that was merged. Instead, the team opted to generalize this functionality so that any feature utilizing the customizer controls can do partial preview updates. Widgets still get live previews, but the window will refresh in an unobtrustve way as you make changes. Now that the widget customizer will soon be a native part of the WordPress publishing experience, WordPress users should be sure to read up on all the capabilities it will add.