Modifying X windows "select" behaviour

Question

Using Linux with KDE

If I double-click on a "B" in the string "AAA,BBB,CCC" then BBB is selected.

If I double-click on a "B" in the string "AAA-BBB-CCC" then the whole string is selected.

How can I change the characters that delimit a word? In other words, I would like to add "-" to the characters the define a word.

Thanks in advance.