Steps to reproduce the error:

1) Compile and run attached "MenuTest" demo
2) In MenuTest JFrame, press 'Alt+T' to get into "Tools" menu
3) Now press 'A' to select either "About" or "About 2" item
--> "Refactor" menu is selected, which is unexpected and wrong. Ideally repeated pressing of 'A' should cycle selection between two items with conflicting mnemonics

Note that it seems to work OK on Windows, error appears only on Linux (and probably other unixes like Solaris as well)