FULL PRODUCT VERSION :
9.0.1

ADDITIONAL OS VERSION INFORMATION :
Win10 x64

EXTRA RELEVANT SYSTEM CONFIGURATION :
Java 9.0.1

A DESCRIPTION OF THE PROBLEM :
The right ALT key has extra bits set when calling KeyEvent.getModifiers() which causes ALT + ? hotkeys to fail.
Even Swing dialogs like JOptionPane.showMessageDialog() don't work (ALT+N ALT+Y don't work).
Only the right ALT is affected.

REGRESSION. Last worked in version 8u152

ADDITIONAL REGRESSION INFORMATION:
1.8_152

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Upgrade to 9 or 9.0.1 and right ALT no longer works as expected.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Right ALT works.
ACTUAL -
Right ALT returns ALT_MASK and ALT_GRAPH_MASK bits.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
JOptionPane.showConfirmDialog(this, "Do you wish to save file?", "Confirm", JOptionPane.YES_NO_CANCEL_OPTION)
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Downgrade to 8.0