Error Report
W3C Validator
In iCab it is also possible to call the HTML and CSS validator of the W3C (World Wide Web Committee) to get the list of errors in the currently displayed web page. To check for errors, just pick the menu item Tools > W3C HTML/CSS Validator. The validator results will be opened in new Tabs (one for the HTML code and one for the CSS code of the site).
Please note that calling the W3C Validator requires that the web page you want to check must be accessible from within the internet. You can't check files that are stored on your local hard disk.