[Lazarus] Keys on Save confirmation prompt not fully working

[Jürgen Hestermann]

When I close a modified unit file within the Lazarus IDE I am asked
whether it should be saved or not with a message window which has
the following 3 buttons:

Save
Discard changes
Abort

While the [S]ave can be selected with the keyboard by pressing S
(and the S is underlined to indicate this) the other two options cannot
be selected with the keyboard. A bug?