Cocoa: Simultaneous fullscreen toggle & opening of modal dialog fails

Does Cocoa have documentation that describes why this functionality is not supported? To try it out is simple, create a default application that uses Objective C in XCode, add a button that toggles the window into fullscreen and opens a modal save-as dialog at the same time. The fullscreen transition will half-complete but kick the application out of fullscreen instantly. Is this expected behavior? The test application is attached below.

The reason why I'm asking this is because real world applications use Cocoa and seem to have pretty severe issues because of this and I am just looking for confirmation from 3rd party, or someone that this indeed is an issue (or simply just the intended behavior, because it can't support it or something like that).

Cocoa: Simultaneous fullscreen toggle & opening of modal dialog fails
 
 
Q