Of course, code would be nicer, but we realize that the divide between developers and user interface contributions might not allow this to happen. Ideally this will expand as things are developing, so all the ideas would get stored here as a resource for future needs. Mockups could be screenshots, or .glade files. Not only this, but they provided animated versions that allowed us to see what was needed. We also need to put together a small and precise checklist that could help people develop good user interfaces, the check list should be used by applications developers as a resource they can go to make sure their application is as good as it can be.
Standard mouse bindings for actions.
Standard help elements. Try to use the following stock icons, etc, etc. Try to use these keybindings, etc, etc. Some of these are easy to do, as gnome-libs helps addressing them. How kind of feedback your app should have.