Select all not working in native FileChooser


In our application we're using the FileChooser to open up a save dialog. Everything is working except that the user is not able to use the keyboard shortcut command+a to select everything they've typed into the "Save As" text input.

It seems to be something to do with the modal state, since whenever I try to use this shortcut I get the system warning beep. Other applications (ProTools for instance) use the native system save prompt in a modal state, however you can still access this keyboard shortcut and are able to click the application's menu bar. The menu bar is locked in our application while the save prompt is open, so that might point to the answer. Any ideas?