Thoughts

Since the post-Opera9.5alpha1 release, Opera supports APNG. Now I was looking which standards Opera support or not. I found interessting pages and I thought what will come in the next releases. But I was also thinking about supporting standards in future releases (not only Opera9.5).
Here is my list I could collect. Two weeks ago I posted Operas compatibility to other browsers and noticed that not standarded tags were good to supported (old tags, which are on old historical pages)
My list also shows the status of the actual status of implemention of standarded scripts (sometimes the results rely on Opera9, sometimes on Opera 9.5alpha) I tried to get a full list with my resources or test-cases!) As you can see here(for graphics support and here(for script-languages) Opera should support all to get the list full and have no problems with othe browsers

graphics-Support
- JBIG 2
- JPEG 2000 (only Webkit native-support at this moment)
- MNG (only KHTML native-support at this moment)
- JNG (only KHTML native-support at this moment)
- PNG support (missing support for: Gamma correction for iCC-profile[tasman-support]; Color correction[tasman-support]; Interlacing; Integrity checking)
- full svg (at that time: 93,4%)(img tag)(In Opera9.5)
- animated svg in css
- SVG as a background gradient
- Rounded corners using border-radius
- Border-image(Safari supported!)
- Animated Favicons (at that time only Firefox supports)

Web standards
- HTML 4.01 (at that time: 86%)
- XHTML 1.0 changes (at that time: 92%)
- XHTML 1.1 changes (at that time: 58%)
- DOM (at that time: 84%)
- CSS 2.1 (at that time: 94%)
- CSS 3 changes (at that time: 19%) [web fonts]
- @font-face
- Opacity (rgba and hsl / hsla)
- resize
- text-justify:newspaper
- word-break:break-word
- box-shadow
- Multi-column
- text-stroke

Protocols
- native wais and gopher support
- better FTP-client
- better torrent-client
- PIM support
- BiDi support

other
- native Mikroformat
- native PDF support(not only at mac!)
- a build-in support for wmp/quicktime/etc

Resources
SVG support
HTML; XHTML; CSS2.1; CSS3 changes; DOM