JInternalFrame in Motif Look And Feel don't show system menu on single right click on System menu area(Top left)
Steps to reproduce:
 - Run SwingSet2 demo.
 - Change Look and feel to Motif Look And Feel.
 - Now single right click on any internal frame's System menu area(Top left), nothing happens, But if we compare with native than it displays System menu on right click.
 Since: All versions of jdk