If you wrap a JTable in a JLayer, the cursor is moved to the last row of table by you press the page down key.

FULL PRODUCT VERSION :
java version "1.8.0_102"
Java(TM) SE Runtime Environment (build 1.8.0_102-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.102-b14, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Windows 10 Pro

A DESCRIPTION OF THE PROBLEM :
This is because of a problem in javax.swing.plaf.basic.BasicTableUI. If you look around line ~427 you will see this code:

Dimension delta = table.getParent().getSize();

It should be as follows:

Dimension delta = SwingUtilities.getUnwrappedParent(table).getSize();

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Run the code : http://bugs.java.com/bugdatabase/view_bug.do?bug_id=7068740
2. Select first row.
3. Press the page down key.


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
(25,0), (25,1), (25,2) row was selected.
ACTUAL -
(99, 0), (99, 1), (99, 2) row was selected.

REPRODUCIBILITY :
This bug can be reproduced always.