If you type "about:Mozilla" in the URL bar (without the quotes), it will display the dialog "Hey, this is not Netscape’s Navigator!!!"
One of the features of iCab is the smiley face in the menu barthat displays the errors in the page source.
Shift-click on it.
Depending on if there are errors in the page, you will hear one of three things;
If the face is happy it will say "Ooh!... more