As of now, on my pixelbook, when the cursor is in the shortcut field of the snippet editor, the <tab> key takes me to the bold formatting icon. A better place to land would be the snippet body editing field.
Also, it would be nice if a click in (or tab to) each field highlighted the default contents, making replacement of the default text just a matter of typing. Of course, that might lead to catastrophic errors when editing an existing snippet. So how about omitting "New Snippet," "/do," and "Replace me..." altogether. Place the help text in the field labels instead.