Annual Documentation Survey
Builder 4.0.0 removes usage of the problematic ext-js library and adds builder resources, zipped layout backups, syntax highlighted CSS, JS & HTML editing (through the use of the fantastic CodeMirror library), support for confluence 3.1, i18n customisation and much more...
Requires confluence 3.1
If you have a Builder 3.x customised dashboard then you should use the rebuild tool on the backup tab of builder admin to import the custom dashboard content to the new dasboard.wiki layout-resource structure
Don't forget to upgrade to latest Page Information Tools and Content Formatting Macros plugins as those also have new releases for Confluence 3.1.