Back button does not work on Files & Folders (it is not actually a back button)

I am not sure should that button act as a Back button in the first place. I hope so, as this is the purpose of the left arrow button, in the top left corner, in every known modern desktop application.

There is a design aspect to this bug, to determine whether to present the back/forth buttons in all cases.

For Maverick, I propose to just make the buttons 'inactive' state a bit more obvious, so that users feel less tempted to use them.

@macslow: can you update the opacity level of the buttons when in the inactive state, to use an opacity value similar to the one used in other parts of Unity to express the same inactive state (menu items for example).

This bug was fixed in the package unity - 0.2.42-0ubuntu1

---------------
unity (0.2.42-0ubuntu1) maverick; urgency=low

  * New upstream release:
    - "Applications" and "Files & Folders" tooltips are not translatable
      (LP: #644215)
    - Fix inactive menus are accessible on switching to a window (LP: #604505)
    - Fix wrong launcher tile label/quicklist x position (LP: #631446)
    - Fix highlighted items in quicklist have different widths (LP: #643315)
    - In migration tool, being safe when people are using crazy caracters in
      desktop file (LP: #644114, #635156)
    - Detect if 3D acceleration support is provided. Otherwise, prompt for
      logout and change default session (LP: #614088)
    - Fix quicklist shows hidden menu items (LP: #641543)
    - Fix removing launchers via dnd fails (LP: #643434)
    - Better launcher auto-scroll performances (LP: #640560)
    - Make the insensitive state of the forward- and back-button more obvious by
      decreasing their opacity, thus users don't assume they are actually
      clickable. (LP: #638285)
    - Fix some dialogs aren't maximized but are undecorated (LP: #628822)
    - Fix some menus don't go away when window closes (LP: #640557)
    - Fixes bug where the wrong icon where at times associated with a tile in
      the places view. (LP: #642935)
    - Speedup icon loading (LP: #641246)
    - Make trash menu items in Unity are either not translatable or translations
      are not loaded (LP: #645038)
    - Fix using dnd on launcher makes focus not work out of the unity ui
      (LP: #637123)
    - Multi-monitor support (LP: #637123)
    - Enable/disable super key by a gconf key (LP: #632581)
    - Remove glow on fold (LP: #619344)
    - Ensure we dont map windows when expose is active (LP: #599766)
    - take new indicator API for action for top-level dropdown menu item not
      activated (LP: #637692)
    - Make the home buttons reactive (LP: #638857)
    - Add red tint when search fails (LP: #607821)
    - New (and final!) UI adjustement, but UNE isn't in the doc as seen with
      the doc team (LP: #627009)
    - Single-touches on the launcher are usually interpreted as a drag
      (LP: #641328)
    - URI activation in global view (LP: #612562)
    - Clicking a Place icon while viewing the same place in the Dash should
      return to the Home screen of that place and clear the search (LP: #607829)
    - Fix mutter crashed with SIGSEGV in g_type_check_instance() (LP: #641561)
    - Fix panel and menu item font colors don't match (LP: #637480)
    - Fix indicators have orange color (LP: #632975)
    - Fix inactive menus are accessible on switching to a window (LP: #604505)
    - Use semi-transparent rectangle around launcher-icon (LP: #643388)
    - Fix mutter crashes when closing pop-up dialog (LP: #642669)
    - Change launcher icon reference size loading (LP: #641669)
    - Fix mutter crashing in mumble start (LP: #641335)
    - Fix clicking on a category from CoFs does not directly take you to the
      desired category (LP: #638402)
    - Fix some menus don't go away when window closes (LP: #640557)
    - Launchers should act like if the application was not focussed ...