<Swing Dev> [10] RFR JDK-7190539:Nimbus LaF: JPopupMenu reacts on Ctrl+Enter.

[Prasanta Sadhukhan]

Hi All,

Please review a fix for an issue where when a JPopupMenu is displayed, 
an underlying Default JButton still responds to the CTRL-ENTER keystroke
for NimbusLookAndFeel.
This is a continuation to JDK-4870644 fix where it is fixed for Basic L&F.
The problem there was that we do not override ctrl ENTER action that 
registered in the patent container as "press default button".
The idea of the fix is to override this binding with the "press selected 
menu item" action.

The same fix is extender to Nimbus L&F.

Bug: https://bugs.openjdk.java.net/browse/JDK-7190539
webrev: http://cr.openjdk.java.net/~psadhukhan/7190539/webrev.00/

Regards
Prasanta