How does OSX tell what app to open when you double click a file?

David V Glasgow dvglasgow at
Wed Aug 7 05:31:17 EDT 2019

No idea if this is any help at all, but I run two versions of Apple Pages (I have my reasons… ;-)

I have the older version set as the default for all Pages documents, and make exceptions when I need to.  Interestingly, MacOS 10.13.6 gets confused sometimes.  Even if a document is set to open with the newer version, some launch the older version.  Can’t always see why.

They also always open with the older version, if that version is already open, irrespective of the setting in Get Info.  Except if you use “open with” 8.1, then the later version is launched and used.

I have also noticed that some docs are set to open with the older version with the text in the get info 'open with' drop down menu saying 

Pages (Default) (4.3)

Whereas others just say

Pages (4.3)

I can’t work out if there is a difference between the two, but the drop down menu also normally offers 

Pages (Default) (8.1) 

Which is only effective if 4.3 is not open

So this looks like a dark art not even the Apple Developers have mastered.  Although I guess they would argue that no one in their right minds runs more than one version of the same app. 


David G

> On 7 Aug 2019, at 3:10 am, Mark Waddingham via use-livecode <use-livecode at> wrote:
> On 2019-08-06 23:59, Paul Dupuis via use-livecode wrote:
>> For example, if you drag installed 5 apps, APP1, 2, 3, etc, that all
>> had a info.plist defintion for a .xyz file extension onto a virgin OSX
>> system out of the box and then double-clicked a .wyz file, which of
>> the 5 would open?
> I *think* the answer to this question probably lies here:
> The sections on 'Application Registration' and 'Preferred Applications' are probably the most pertinent - although it isn't entirely clear how the two mechanisms co-exist: registration suggests the 'most recent' modification time wise app is stored against a file kind, but preferred applications suggests that multiple apps are stored but the newest CFBundleVersion wise is chosen.
> Warmest Regards,
> Mark.
> -- 
> Mark Waddingham ~ mark at ~
> LiveCode: Everyone can create apps
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