QUOTE
Can the HTML tag dictate whether a new tab, rather than a new window, is opened? I greatly prefer tabs, but since many pop-ups make no sense as tabs (and may resize the viewing window(!)), I must leave my default browser setting to open windows. Managing separate windows, however is a pain, so I'm strongly opposed to forcing a new tab/window to be opened for input.
UNQUOTE

Interestingly enough, there are Firefox plugins that when certain of their settings are enabled, can force all 'open in new window's to 'open in new tab's - eg 'Tab Mix Plus', which is one I use on both Windows (7) and Ubuntu.