FULL PRODUCT VERSION :
java version "1.6.0-beta2"
Java(TM) SE Runtime Environment (build 1.6.0-beta2-b79)
Java HotSpot(TM) 64-Bit Server VM (build 1.6.0-beta2-b79, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
2.6.12.2 Linux kernel for Debian AMD64

A DESCRIPTION OF THE PROBLEM :
  From <http://www.netbeans.org/issues/show_bug.cgi?id=74008>:

Mustang build 1.6.0-beta2-b77 (i586 and AMD64 for Linux) disables double click
word selection with Netbeans 5.0 build 200601251500. Double click a word and
the word is not selected.

Lack of double click word selection reconfirmed with AMD64 b79 build.

REGRESSION.  Last worked in version mustang

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Background of a word turns grey ("selected") after double-clicking upon a word.
ACTUAL -
Word remains unselected.

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
Revert to the b75 builds.  I can confirm that the b77 and b79 builds disable double click word selection. I have not downloaded/tested whether the b76 or b78 builds disable double click word selection.