=== Behavior ===
 * Each extra should provide its own palette.
 * All created book extras should be listed in the Book Extras palette.
   * there must be either visual marker or label that shows whether the extra is visible or not
 * Book extras should support drag and drop
  * drag extra from the file system to Sophie should import the extra
  * drag extra from Sophie to the fike system should export the extra
=== Existing book extras ===
 * Stickies
  * Stickies should support text styling (these depend highly on text).
   * Bold (Ctrl/Command + B)
   * Italic (Ctrl/Command + I)
   * Underline (Ctrl/Command + U)
   * These are to be decided whether we should support them when the text is pasted into the sticky
    * Striketrough
    * Text color
    * Background color
    * Font
  * Stickies should provide copy/paste functionality for text with style.
  * Stickies must be listed in the stikies' palette (at the moment this palette contains only one button and its pointless).
  * A couple of predefined colors changing with one click (because of the styled text yellow maybe not so good for some cases).
  * Stickies halos must be with similar styling to the rest of the application (now the icons, look like from other application).
=== Import and export of book extras ===
 * Probably it is a good idea the book to has some id that is used by the book extras
  * At the moment each time the user saves the book ref is changed and the stickies are no more associated to that book.
 * Some problems that may emerge
  * (Stickies related) When page is deleted and book extra (sticky set is imported) the stickies corresponding to the missing page shouldn't be displayed.
=== Possible future book extras ===
 * Bookmarks (similar to the ones in .pdf files)
  * Something like a quicklinks that the user can create for easier navigation within the book.
 * Highlights
  * These were planned originally for Sophie 2.0. They give the readers possibility to highlight certain text pasages.
 * Media (audio and/or video) annotations
  * Similar to the stickies but instead of a text they contain video or audio that the reader want to place somewhere in the book.
 * Additional frames added by the users but not part of the book (like a whole book page)
  * Sample use case: Book containing some Problems which solutions are more complex and contain graphics.
 * (not so sure about these)
  * Correction vizualization
  * Spyglass
   * Something like a frame that zooms only the content behind it. An accessability feature that may come handy to some users with eye problems.