launcher auto-scroll performances

See also where user are reporting that the scroll is too slow: https://bugs.launchpad.net/unity/+bug/638314

Merging the 2 bugs into one single task for adjusting the scroller.

Christian: we'll need your input to update the formulla.

David, the problem is not with the formula which is far from being CPU intensive.

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

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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 ...