Yes, everything which has a relative URI is not recognized by IE in this special mode. I have already reported that during beta test phase and IDM has promised that the developers will look into it and try to find a solution for that problem.
In detail something like:
<link rel="stylesheet" href="../main.css" type="text/css">
<img src="../images/valid-html401.png" width=95 height=43 alt="valid HTML 4">
is currently (UE v13.00+2) not recognized and loaded in the browser view mode. A workaround is to use following in the head section of every file:
Of course, I can't use this workaround because it requires a permanent online connection and I don't like that and for one of my HTML project this is not possible because the HTML files are only for company internal usage and so only for offline browsing.
At the moment I still open with Ctrl+3 (user tool) my current file in Opera and switch with ALT+TAB to Opera and press F5 (or ALT+F5 when frames also loaded) to reload the before saved file in UE/UES and switch with ALT+TAB back to UE/UES.