Preface
Since Ubuntu 8.04 (Hardy Heron) the USB aluminium Apple Keyboard has not worked correctly. A change was added to the Ubuntu Linux kernel to make Apple MacBook keyboards gain additional functionality to their limited laptop style keyboard (Ubuntu bug #162083). Unfortunately this code change has some side effects for owners of the full size USB aluminium Apple Keyboard:
* Function keys have media functions as default. The "fn" key must be pressed and held to access the F-key functionality (except F5 and F6, which are inverted in this respect). (Ubuntu bug #201711)
* Num lock key will when pressed render the keyboard seemingly unusable. The keyboard will simulate a numeric keypad on the alphabet keys. Pressing F6 twice will exit this mode. (Ubuntu bug #201887)
* Two keys are swapped on international (non-US) keyboard with respect to the printing on the keycaps. (Ubuntu bug #214786)
* Bug filled by me in the main kernel bugzilla http://bugzilla.kernel.org/show_bug.cgi?id=10818 Please help if you think (as I) that the kernel developers are wrong, assuming that the keyboard have to behave like under MacOS.
Corrections
Correcting the Function Key and Num Lock issue
* Edit the file /etc/modprobe.d/options, e.g.:
sudo gedit /etc/modprobe.d/options
* Add the line: options hid pb_fnmode=0
* Save the file and execute the following command:
sudo update-initramfs -u
* Reboot
Correcting the two swapped keys for international (non-US) keyboards
* Open the 'System->Preferences->Keyboard' dialog
* Choose the 'Layouts' tab
* Press 'Layout Options...'
* Navigate to 'Miscellaneous compatibility options'
* Enable the option: Swap keycodes of two keys when Mac keyboards are misdetected by kernel.
Belgian Macintosh Keyboard Layout
Take a look at https://help.ubuntu.com/community/Macbook_Air#head-5fd0bcf04cc7da0b5241950916bab5d58cdb84da in the Belgian Keyboard section
Postscript
These issues may also apply for the Bluetooth aluminium Apple Wireless Keyboard.