Comment 28 for bug 67188

I confirm this too. After system rebooting I have to go on System>Keyboard>Layout disposition and click on Apple Laptop to have accentuation working again for brazilian characteres.
mabovo@macbook:~$ xprop -root | grep XKB
_XKB_RULES_NAMES_BACKUP(STRING) = "xorg", "macintosh(macbook79)", "pt", "mac", ""
_XKB_RULES_NAMES(STRING) = "xorg", "apple_laptop", "us", "basic", "grp_led:scrol l,compose:rwin,lv3:lwin_switch"
mabovo@macbook:~$ gconftool-2 -R /desktop/gnome/peripherals/keyboard/kbd
 layouts = [us basic]
 model = apple_laptop
 options = [grp_led grp_led:scrol l,Compose key compose:rwin,lv3 lv3:lwin_switch]
 overrideSettings = true

Section "InputDevice"
 Identifier "Generic Keyboard"
 Driver "kbd"
 Option "XkbRules" "xorg"
 Option "XkbModel" "macintosh(macbook79)"
 Option "XkbLayout" "pt"
 Option "XkbVariant" "mac"
# Option "XkbOptions" "lv3:ralt_switch,grp:alts_toggle,grp_led:scrol l"
EndSection

[ 25.821317] input: Apple Computer Apple Internal Keyboard / Trackpad as /devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/input/input1
[ 25.829802] input,hidraw0: USB HID v1.11 Keyboard [Apple Computer Apple Internal Keyboard / Trackpad] on usb-0000:00:1d.0-2
[ 25.833010] input: Apple Computer Apple Internal Keyboard / Trackpad as /devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.2/input/input2
[ 25.841775] input,hidraw1: USB HID v1.11 Device [Apple Computer Apple Internal Keyboard / Trackpad] on usb-0000:00:1d.0-2
[ 25.847261] hiddev96hidraw2: USB HID v1.11 Device [Apple Computer, Inc. IR Receiver] on usb-0000:00:1d.2-2
[ 25.864396] input: HID 05ac:1000 as /devices/pci0000:00/0000:00:1d.3/usb4/4-1/4-1:1.0/input/input3
[ 25.873717] input,hidraw3: USB HID v1.11 Keyboard [HID 05ac:1000] on usb-0000:00:1d.3-1
[ 25.888216] input: HID 05ac:1000 as /devices/pci0000:00/0000:00:1d.3/usb4/4-1/4-1:1.1/input/input4