Launch of multiple application instances (Mac vs Win)

Paul Dupuis paul at
Sun May 8 12:08:35 EDT 2022

The LC 9.6.7 Dictionary entry to 'relaunch" states:

It can be used in the following three ways:

|1. If the message is passed, then the new instance continues running. 
2. If "background" is returned, then the new instance is terminated. 3. 
If nothing is returned but the message is not passed, then the new 
instance is terminated and the existing instance's "defaultStack" is 
made the foreground window.|

If there are no existing instances, the new instance will run.

1. seems pretty straightforward:

on relaunch

   pass relaunch

end relaunch

Would allow the 2nd (or whatever number) instance to continue to start up

3. Seems obvious as well:

on relaunch

   -- trap the message

end relaunch

Here, the message is not passed, so the new instance is terminated and 
the "defaultStack" of the existing instance is brought to the foreground

However, I do not understand 2. What the heck does ;If "background" is 
returned" mean in the context of this handler? Returned from what? The 
only example given is:

onrelaunch pDocument openDocument pDocument endrelaunch

And the Dictionary states that actually multiple parameters can be 
passed (for example if multiple documents where dragged onto the app to 
launch it). I feel there is something missing in the Dictionary entry!

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