this report has been opened here:

https://bugs.edge.launchpad.net/ubuntu/+source/gnome-terminal/+bug/352395

"According to the the Gnome Terminal documentation at http://library.gnome.org/users/gnome-terminal/stable/gnome-terminal-prefs.html.en

Select-by-word characters
Use this text box to specify characters or groups of characters that GNOME Terminal considers to be words when you select text by word.

I currently have the default Select-by-word characters: -A-Za-z0-9,./?%&#:_=+@~

Before upgrade to 9.04 (GNOME 2.26), I could select the text before or after the a Select-by-word character, now it will select the entire "word", before and after the symbol, including the symbol.

Example:

words.before.at@words.after.at

On GNOME 2.24:
Action, double click the word "before" would select "words.before.at"
Action, double click the word "after" would select "words.after.at"

On GNOME 2.26:
Action, double click the word "before" selects "words.before.at@words.after.at"
Action, double click the word "after" selects "words.before.at@words.after.at"
"

Removing or adding the @ to the select-by-word doesn't make any difference.

thanks in advance.