Show Startup Panel like XCode in Lion

My app at launch time prompts the user with a template chooser, this works fine on Snow Leopard but on Lion the window never appears maybe due to restoration behaviour.

My app is NSDocument based and I use NSDocumentController to open the window on newDocument:(id)sender

Now on Lion no application delegate related to "untitiled" is called so I don't understard how to make it working

I think XCode 4 is NSDocument based and it shows the Startup Panel, how it does?

Another smart XCode Startup Panel's behaviour consists to show the panel only when n开发者_C百科o other windows are restored, again how this is implemented in Lion?

You're right to suspect the new restorable state behavior. The app may never be asked to create a new, empty document when relaunched/resumed. This is stated in the release notes:

As part of the restorable windows feature, the application delegate may not be asked to create an Untitled window at launch in some circumstances. This was found to cause crashes in certain apps, so these apps will maintain 10.6 behavior of more often opening Untitled windows. When these apps are recompiled on 10.7, they will acquire the 10.7 behavior. For maximum compatibility, do not depend on being asked to create an Untitled window at launch.

They don't mention an alternative, and the document-based app documentation does not appear to have been updated yet with restorable state information.

As to your approach, you could change so that the template chooser is shown as a sheet on a new, empty doc window (like Pages or Instruments, for example). The document's contents are set when the template sheet is completed. This way, each new document shows its template sheet but this only happens if the user requests a new document, rather than relying on a fresh app launch (which you're no longer meant to do).