FreeDOS Edit 0.9a does not recognize the right ALT key if nothing is highlighted in the menu bar (such as when editing text) -- only the left ALT key is recognized. If any entry in the menu bar is highlighted, the right ALT key is recognized.
I'm experiencing the same problem, but with both left and right Alt keys. I'm using an Accuratus KYB500-K82D USB combo trackball/keyboard. I've also tried a similar Cherry G84-5400LUMGB-2 combo USB keyboard.