--- old/src/java.desktop/share/classes/com/sun/java/swing/plaf/motif/MotifLookAndFeel.java	2018-04-10 15:05:54.501209999 +0530
+++ new/src/java.desktop/share/classes/com/sun/java/swing/plaf/motif/MotifLookAndFeel.java	2018-04-10 15:05:54.225209999 +0530
@@ -636,7 +636,9 @@
             "Menu.submenuPopupOffsetX", -2,
             "Menu.submenuPopupOffsetY", 3,
             "Menu.shortcutKeys", new int[]{
-                SwingUtilities2.getSystemMnemonicKeyMask(), metaMask
+                SwingUtilities2.getSystemMnemonicKeyMask(), metaMask,
+                SwingUtilities2.getSystemMnemonicKeyMask() |
+                        InputEvent.ALT_GRAPH_DOWN_MASK
             },
             "Menu.cancelMode", "hideMenuTree",
 
