How to listen to System-wide Open and Save Panel Events?

Question

Is there any way to listen for system-side open and save panel events and respond to it, similar to how Default Folder X does it? Does this require private APIs or runtime code replacement? Or can it be done using publicly available APIs?

Answer 1

I don't think it can be done with public APIs. The FAQ for Default Folder X says:

Default Folder X does not patch Mac OS X, but it does extend individual applications when they are launched. This means that Default Folder X loads a small piece of program code into each application's memory space (in RAM) so that it can communicate with Navigation Services, the OS X service that provides the Open and Save dialogs.

That suggests to me that it's using code injection.