Fixed in this release

• Discussions real-time update could slow down Confluence server with Talk 2.2.0-2.2.1.
• Talk icons aren't displayed in PDF export of a page now.
• Confluence 5.6 compatibility is improved. Archived discussions on a page could lead to odd warnings in the editor.
• Firefox compatibility is improved. In some cases discussion sidebar could be erroneously hidden.
• Documentation theme compatibility is improved. In some cases Talk could change left sidebar width accidentally.