Following is probably only important to people who use SemanticScuttle in conjunction with keyboard browser navigation tools (e.g., Gleebox). In short, this is a tweak to SemanticScuttle that causes the "Tags" field to be focused when the pop-up window appears.
I think that the original author intended for this to occur in any case, as the word "focus" is in the field declaration. It may have later become non-functional after a tweak to HTML (1.1?) or Chrome.
In any case, in your SemanticScuttle folder, find data/templates/default and edit the file called "editbookmark.tpl.php". Find the line that contains "echo T_('Tags');". Two lines below that should be a HTML form input field with the name value of "tags". In that line, change "focus" to "autofocus" and the SemanticScuttle popup should function as intended.