Appendix 1: Internet Explorer 6 to Internet Explorer 8 browser changes

The following table describes changes between Microsoft Internet Explorer 6 and Windows Internet Explorer 8.

Design changes from Internet Explorer 6 to Internet Explorer 7

Design changes from Internet Explorer 7 to Internet Explorer 8

${ROWSPAN2}$Internet Explorer versioning${REMOVE}$

Check for code that incorrectly special cases around Internet Explorer 6, Windows Internet Explorer 7, or Internet Explorer 8 through user-agent string sniffing, versions vectors, or conditional comments.

  • When a long User Agent (UA) String encounters a server that accepts only shorter UA Strings, users see an error page.
  • The Compatibility View in Internet Explorer 8, which is turned on by default for intranet sites, sends a Internet Explorer 7 user agent string. To differentiate between Internet Explorer 7 and Compatibility View, look for the new Trident token.

${ROWSPAN3}$ Standards compliance updates


Quirks mode exception: You do not need to make standards compliance changes for webpages that specify the quirks mode DOCTYPE (by setting the “standards-compliance” DOCTYPE switch to “off”).

Applies to Internet Explorer 7 Standards or “Strict” mode and above:

Applies to Internet Explorer 8 Standards mode and above:

Security improvements

  • Apply regardless of document mode.
  • You can turn off security features by using Group Policy.

Architectural changes

  • Apply regardless of document or compatibility mode.
  • Protected Mode Update: Intranet runs in medium (instead of low) integrity level by default.
  • Loosely Coupled Internet Explorer might block add-ons (that is, ActiveX controls and COM objects) that do one of the following:
    • Use windows hierarchy techniques to locate UI frame and tab windows (which now run in separate processes at different integrity levels).
    • Create a subclass of the UI frame (now at medium integrity level) from a low-integrity tab process.
    • Use unsupported messaging techniques between UI frame and tabs.


Addressing Application Compatibility When Migrating to Internet Explorer 8