function _handleNewRuleClick(e) {
            if (!newRuleButton.$button.hasClass("disabled")) {
                if (cssFileInfos.length === 1) {
                    // Just go ahead and create the rule.
                    _addRule(selectorName, cssInlineEditor, cssFileInfos[0].fullPath);
                } else {
                    // Although not attached to button click in 'dropdown mode', this handler can still be
                    // invoked via the command shortcut. Just toggle dropdown open/closed in that case.
                    newRuleButton.toggleDropdown();
                }
            }
        }
@private
Create a new rule on click.