A DESCRIPTION OF THE PROBLEM :
In the resource bundle 'com.sun.swing.internal.plaf.basic.resources.basic_fr.class':
the properties for 'InternalFrameTitlePane.minimizeButton.textAndMnemonic' and 'InternalFrameTitlePane.restoreButton.textAndMnemonic' have the same mnemonic (VK_R).

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Using the French locale :
Using an InternalFrame with basic, Synth, or Windows LaF, and right-clicking the title bar.
You can also see the problem while querying UIManager.getString("InternalFrameTitlePane.restoreButton.mnemonic") and UIManager.getString("InternalFrameTitlePane.minimizeButton.mnemonic") returns both '82'
Metal overrides these keys (using R and D instead of R and R).

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Having different mnemonic for "Réduire" and "Restaurer".
ACTUAL -
I have the same underlined character for those menu items.

---------- BEGIN SOURCE ----------
System.out.println(UIManager.getString("InternalFrameTitlePane.restoreButton.mnemonic")); // 82
System.out.println(UIManager.getString("InternalFrameTitlePane.minimizeButton.mnemonic")); // 82
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Using the up and down arrows instead of the mnemonics.

FREQUENCY : always