[7u10] Review request for 7160951: [macosx] ActionListener called twice for JMenuItem using ScreenMenuBar

[Leonid Romanov]

Hi,
Please review a fix for 7160951: [macosx] ActionListener calle	d twice for JMenuItem using ScreenMenuBar.  Although a number of files have been changed, only CMenuItem.m changes constitutes the fix, the rest of the changes is a bit of code cleanup.
The fix has been contributed by Marco Dinacci. Thanks!

Bug: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7160951
Webrev: http://cr.openjdk.java.net/~leonidr/7160951/webrev.02/

Thanks,
Leonid.