I just wanted to share this with you, so here are some useful Extensions that bring back features that were abandoned in the latest Opera and some useful functions that the old Opera 12 had.

If you know anything else, just let me know here and I will update the post.

1. bring back recently closed tabs:
   Wrona History Menu
   Undo Closed Tabs Button

2. show image properties:
   Classic Context Menus
   Classic Images

3. switch tabs with right-click + scroll (buggy, doesn't work on all sites):
   Opera 12-like tab switcher

4. auto-reload page:
   Classic Context Menus (steps: none, 1m, 5m, 30m 60m)
   Tab Auto Refresh (1s steps)

5. site specific preferences:
   Site-specific Preferences

6. user style sheet:
   Stylus

7. turn all images on/off:
   Images ON/OFF

8. turn JavaScript on or off:
   JavaScript Switch ON|OFF

There may be more Extensions, but these are the ones I use mostly.

I also made a little website where you can test your Extensions: 1info.tk

Hope this helps