Minecraft wiki entry for Development_versions, associated text: Added "Saved Toolbars" tab
Save toolbars in Creative Mode with Ctrl+1-9/⌘ Cmd+1-9 and load them with ⇧ Shift+1-9.
Can save up to 9 toolbars.
If an empty toolbar is saved, it will clear the bookmarked toolbar and put back the 'informational paper' in the respective slot.