TODOs:
- convert into HTML
- maybe display inside a R77 specific help dialog (from Command dialog)
- check if Command dialog and Settings shoud use the same button (16:9,4:3)
- explain Command and Settings dialog
- explain Power-on options dialog (or refer to Stella User's Guide)

*** Navigation ***

Stella can be controlled via the console buttons or a joystick in left or
right port.

During emulation:
  The joysticks work normal and all console buttons as labeled except of the
  following.

  Joystick  īButton      Action
  ----------------------------------------------
  Button 3   4:3,16:9    Open the command dialog
  Button 4   -           Open settings
  Button 5   FRY         Return to launcher
  Button 6   -           Rewind game
  Button 8   MODE        Select
  Button 9   RESET       Reset

Inside Launcher:
  Joystick   Button      Action
  --------------------------------------------
  Up         SAVE        Previous game
  Down       RESET       Next game
  Left       LOAD        Page up
  Right      MODE        Page down
  Button 1   SKILL P1    Start selected game
  Button 2   SKILL P2    Open power-on options
  Button 4   COLOR,B/W   Open settings

Inside a dialog:
  Joystick   Button      Action
  -----------------------------------------------------
  Up         SAVE        Increase current setting
  Down       RESET       Decrease current setting
  Left       LOAD        Previous dialog element
  Right      MODE        Next dialog element
  Button 1   SKILL P1    Select element
  Button 2   SKILL P2    OK
  Button 3   4:3,16:9    Previous tab
  Button 4   FRY         Next tab
  Button 6   -           Cancel

Note: If you have a keyboard attached via OTG all keys work as described in
the Stella User's Guide.