FULL PRODUCT VERSION :
java version "1.6.0-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-beta-b59d)
Java HotSpot(TM) Server VM (build 1.6.0-beta-b59d, mixed mode)

worked with:
java version "1.5.0_07"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_07-b02)
Java HotSpot(TM) Server VM (build 1.5.0_07-b02, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
SunRay (Solaris 10 3/05 s10_74L2a SPARC)

A DESCRIPTION OF THE PROBLEM :

With JEditorPane in combination with PlainDocument in Tiger we have about-2-pixel-width selection of empty rows (see tiger_plain_editor_pane.PNG), while in Mustang we have StarOffice-like selection of lines, i.e. their complete selection, including empty lines (see mustang_plain_editor_pane.PNG).

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1) Compile and run attached bugSOfficeSelection.java
2) Enter some paragraphs
3) Select empty lines with mouse
4) See the difference

EXPECTED VERSUS ACTUAL BEHAVIOR :

EXPECTED -

It should look like in tiger_plain_editor_pane.PNG

ACTUAL -

It looks like in mustang_plain_editor_pane.PNG

REPRODUCIBILITY :
This bug can be reproduced always.