Menu shortcuts don't trigger when keyboard focus is in text field

On Mac OS X 10.8.3, when pressing a keyboard shortcut to trigger a menu item, the menu item is not triggered if the keyboard focus is currently in a text input field. Rather, the key in question is typed in the field. I have attached a small sample app demonstrating this: After opening the app, try pressing command-d to open a dialog. Rather than opening the dialog, the "d" is typed into the text field.