This is occuring on Swing PIT build 6.0-rc-b68.
Regression introduced fix for Bug # 6356402
description :- JTableHeader cells should be painted like buttons.

This is as expected however if I tab to the table header then the selection on the header does not appear Even as I shift focus to the other headers by pressing the arrow key it is still not visible. Change L&F to Java and it shows up clearly.

Step to reproduce:-
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1) Run SwingSet2.
2) Select Table Demo.
3) Click on "Fit Width" JCheckBox.
4) Press Tab key once. you can see the focus is on "Print" button.
5) Press Tab key once again. now the focus is on JTable header. We can't say that
   selection on the header , even i press arrow key. But we can see the particular column
   is selected by press "space bar " key.
This observed only in GTK Look and feel only.