Hi Mr. Eric,
I have myJframe whose windowClosing() metod is overriden as System.exit(0).
After pressing "quickly preview without running" button of WindowBuilder 7.4, myJFrame appears as if it was in runtime.No problem
But the problem is,
if i press the close button of myJframe then myJframe disappears and Eclipse shutDown...
I think,this can be a bug of WindowBuilder 7.4
may be :"quickly preview without running" code must not be run in the same execution-context as Eclipse does
fyi