Hover help via tooltips

[edemaine]

I'd like to add more hover tooltips to existing features, so that documentation is more obvious and prevalent. Some obvious examples:

• Actions
  • Delete/Undelete (could mention that you'll still see it, but others can't, and define visibility model)
  • Publish/Unpublish (ditto)
  • Make Private/Public
  • Superdelete
  • Move
  • Minimize/Unminimize (global folding)
• +/- (user's fold)
• Focus/zoom button
• Attach button: creates a new reply message with the file "inside"; mention ability to drop here
• Replace File button
• Raw
• History
• Should also review what other features are missing tooltips.