The save/cancel buttons on all the Groups UIs aren't disabled on initial click, which can result in impatient users clicking multiple times.
The attached patch simply disables the buttons on click and displays a spinner to notify the user of progress.
I had to take the approach of cloning the buttons, hiding the original and disabling the clones, because if you disable the actual submit buttons, the form will not be submitted. The spinner icon should be added to the reference project so it can be used by all other projects, rather than having an instance of the spinner gif in every project that wants to use it.
The patch also renames some of the button labels for consistency; previously some were called 'Add', others were called 'Update', etc.