I feel more feedback toward the user about the way the joystick mapping feature works could help make it more intuitive.
Currently, it's entirely possible to attempt to map a joystick button to a command without having any joystick(s) assigned; I suggest a dialog box along the lines of "No joystick devices are currently assigned, this needs to be done before it is possible to map buttons", which could also take the user directly to the "Joystick Options" window to do so.
Additionally, when joystick devices are assigned but not connected(only if none are connected), and mapping a button is attempted, a similar dialog could be shown to either remind the user to plug them in, or reassign one of them if a non-assigned joystick is connected.