Review target: https://wiki.automotivelinux.org/_media/eg-ui-graphics/170606_agl_hmi-fw_arch_0_2_3.pdf
  
  * Nobuhiko Tanibata
    * When layout change is triggered by Homescreen, efficient transition animation of surfaces shall be supported.

  * Takashi Matsuzawa
    * The document should describe which part of it is mandatory and which parts are optional/selectable (e.g. I understand that 2 windows up/down layout is just one example of OEM profile - though it is very good that we have one example OEM profile and demo homescreen/window manager is written for it.)
    * Regarding the API calls apps make, the document (or manual document) should clarify them into the following two categories, so that audience can know which part is AGL specific.
      * API calls/actions that ordinal wayand-ivi apps will do (not specific to AGL)
      * API calls/actions that are specific to AGL
    * Graphics toolkits (e.g. Qt or others) here are expected to hide such API details from application developers or not, including AGL additions?

  * Takashi Matuszawa
    * I think the spec should describe what are the concepts that are shown to the end-user and the actions (use-cases) that are provided.  And vendors can freely implement their HMIs but providing what the spec specifies.
      * e.g.
      * HMI should provide following set of applications.
        * 1) "all applications"
        * 2) "currently running applications" (subset of 1, multiple can exist)
        * 3) "currently visible applications" (subset of 2, multiple can exist)
        * 4) "currently active application" (subset of 4, only 1 almost can exist)
      * And HMI should provide actions as follows
        * Show list of all applications, and optionally allow
          * Select (make active) one of them.
        * Show list of currently running applications, and optionally allow
          * Select (make active) one of them.
          * Quit one of them.
        * Show currently visible applications, and optionally allow
          * Select (make active) one of them.
          * Quit one of them.
    * HMI spec should describe if there are class of applications that needs special treatment and what they are
      * e.g.
        * Navigation
        * Audio
        * Rear-camera
    * HMI spec should describe common operations (if there are any, as AGL HMI standard feature)
      * e.g.
        * "back" operation
          * Press "back" button
          * Swipe screen to right
          * (what button/gesture is bound to "back", and how this "back" is interpreted may be implementation specific?)