Name: openBackground

Type: message

Syntax: openBackground <backgroundID> 

Summary: Sent to all background groups when a card they are placed on is opened.

Associations: card

Introduced: 1.0

OS: mac,windows,linux,ios,android

Platforms: desktop,server,web,mobile

Example:
on openBackground theBackgroundID
  -- update content of group
end openBackground

Example:
on openBackground theBackgroundID
   if the short name of this card is "highscores" then
      show button "play again"
   end if
end openBackground

Parameters:
backgroundID: The ID number of the background being opened.

Description:
Handle the <openBackground> message to change a group's objects, or perform other updates, when a card with the group on it is opened.

The <openBackground> <message> is sent to background groups, if there is more than one <group> on the <card>, the <openBackground> <message> is sent to each one.

The <openBackground> <message> is sent after the destination <card> is visible. To make changes that take effect before the <card> becomes visible on the screen, use the <preOpenBackground> <message> instead.

The actual navigation is not triggered by the <openBackground> <message>, so <trap|trapping> the <message> and not allowing it to <pass> does not prevent the <card> with the <group> from opening.

>*Note:*  A group is only considered a background group if its backgroundBehavior property is set to true.

References: backgroundBehavior (property), card (keyword), preOpenBackground (message), openCard (message), startup (message), newBackground (message), closeBackground (message), openStack (message), group (command), pass (control_st), message (glossary), trap (glossary)

Tags: navigation
