Application message type — the vocabulary of user intent for this app.
Every Widget#on_event returns a Msg?; Screen#handle receives a Msg.
One enum per app keeps Crystal's exhaustive case working and lets screens
communicate through a shared vocabulary (e.g. Msg::OpenSearch sent from
the dashboard to the search screen).
Instance methods
advance?
Returns true if this enum value equals Advance
back?
Returns true if this enum value equals Back
confirm_selection?
Returns true if this enum value equals ConfirmSelection
decrease?
Returns true if this enum value equals Decrease
dismiss_notification?
Returns true if this enum value equals DismissNotification
hide_confirm?
Returns true if this enum value equals HideConfirm
increase?
Returns true if this enum value equals Increase
next_screen?
Returns true if this enum value equals NextScreen
open_search?
Returns true if this enum value equals OpenSearch
prev_screen?
Returns true if this enum value equals PrevScreen
refresh?
Returns true if this enum value equals Refresh
select_at?
Returns true if this enum value equals SelectAt
select_next?
Returns true if this enum value equals SelectNext
select_prev?
Returns true if this enum value equals SelectPrev
show_confirm?
Returns true if this enum value equals ShowConfirm
toggle_done?
Returns true if this enum value equals ToggleDone
update_query?
Returns true if this enum value equals UpdateQuery