proxy explanation

what is the option
site preferences: network: use proxy
the default is yes, shouldn't it be no?

The default "use proxy" under Site Preferences simply directs Opera to access that site using whatever connection proxy that has elsewhere been defined under the global Preferences > Network > Proxy Servers panel (if a proxy is defined there) for one's Internet connection for that site, since the global Preferences panel is the only place the proxy's settings are defined in Opera. Otherwise (if a proxy is either not defined under the global Preferences or not selected for use under Site Preferences), a proxy will not be used for connecting Opera to that particular site. In cases where a network proxy is (or must be) used to connect the computer to the Internet, that means that traffic from Opera to that site will not be connected, hence the site will not be accessed.

Think about it. When a user defines a proxy under the global Preferences panel, it's because he intends (or is required) to use that proxy for his Internet connection activity. Consequently, proxy use is pre-checked as the default condition under Site Preferences, unless the user intervenes to de-select it for that site. If the user has not set up a proxy under the general Preferences panel, there will be no proxy present to be used by Site Preferences anyway, regardless of the checkbox status there, so the site will be accessed over such a computer's direct Internet connection. However, there may be unusual situations where a user normally employing a proxy for his connection may not want a given site to be accessed via the proxy, so Site Preferences allows the checkbox to be unchecked if the user so desires. In such cases, the user will have to provide his computer with alternate (direct) Internet connection means for such sites or do without accessing such sites, if he retains use of his proxy in the global Preferences panel.

makes sense, thanks.

@blackbird71

Did you ever test the proxy setting under Site Preferences?
As far as I can tell it is broken. If Opera is set to use a proxy, whatever "use proxy = Yes/No" is set for it makes no difference.

Sorry, my conclusion was hand over head. It works as intended.
I've tested with a filtering proxy. Doing so I overlooked that by visiting a site some resources are loaded from other domains then that specified in Site Preferences.

I guess in either case it's a null value unless a proxy server is manually configured in opera's network settings, though I have not tried the latter.

There may be some sites you don't want to use the proxy for - such as a company site. You'd set Opera to use the proxy normally, and then under Site Preferences you'd say not to use it for this site. If the setting in Site Preferences is ignored, Opera won't be able to open your company site ...

Proxy settings under Site Preferences works as intended. I've edited my post above accordingly.

Originally posted by sgunhouse:

If the setting in Site Preferences is ignored, Opera won't be able to open your company site ...

You mean general Preferences?
The meaning of Site Preferences is to overrule general Preferences. So if you specify a domain in Site Preferences not to use a proxy, your general Preferences where you did set up Opera to use a proxy will be ignored and Opera will connect directly (only) to the respective domain.