So that's one solution - I bet it is what mail.app uses. We could tell by snooping on apple events
Mail has this feature?
Yes. Try cmd clicking a link in an link in an email. It opens in the background, which is very handy. However, I see that it also obeys the app pref to open in a new tab in the existing window if one exists.
As for the AppleScript, for me both Safari and OmniWeb opens the string as file://
My fault for a quick example - the key is that it opens it as file without activating the browser.
Working example =
tell application "WebKit" set theUrl to "http://www.psy.ed.ac.uk" make new document at end of documents set the URL of document 1 to theUrl end tell
But, that needs a new window, not the user's preferred setting (choice of new tab or new window).
The standard additions contain the command "open location" which opens a url but also activates the called app...