I don't know if it's a bug or intended to be like this: I opened 2 pages (on different tabs) from the same domain and zoomed in/out a tab, another tab will also get zoomed in/out.
I remember that on old version (with Presto) this didn't happen.
It's a standard Chromium approach. The architects decided that per-host zoom level setting would minimise the number of zoom operations needed to adjust to each site's design pattern, which is usually the same for its entire domain. Of course, this is not true sometimes (i.e. for blogging platforms, etc.), but serves well with the majority of sites.
Is there any possible way to stop the zooming from affecting entire domains, either in Opera or some extension?
I am frequently frustrated by this behavior. Often when I am viewing a page I will open an image or map in a new tab and zoom in on it. Then when returning to the original page, it is now also changed unwantedly.
I also often find myself wondering why a page looks strange, eventually realizing that on some previous day I zoomed in on a different page that happened to be on the same domain. With no visible zoom toolbar, this is difficult to notice.
Every other Windows program I use treats zoom as a view-specific setting. I wish I could get the same behavior from Opera.