Hitting Enter on focused JButton is not causing any action on Windows OS. This is a very handy feature to improve the user experience of the application. This works in Windows Look and Feel, GTK Look and Feel on Linux but not in Metal, Ran the attached program with the Nimbus Look and Feel on Linux, it is working as expected. The issue is only with Windows OS.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Run the attached program
2. Hit <ENTER> key
3. Notice that there is no System.out