International keyboard settings
To make you keyboard have the accents working for Brazilian Portuguese on Ubuntu in the proper way that Brazilians are used to, you need to add a second Keyboard Layout which uses the English (US, alternative international) language. In Ubuntu 12 or later, that's all you need to do, but folder older versions a hack is required to fix the cedilla.
Debian & Pre Ubuntu 12
On versions of Ubuntu before 12, a hack is required to get the cedilla working. Apostrophe then "C" makes a "ć", which doesn't even exist in Portuguese! It should give the c-cedilla (ç). To fix this final problem you need to edit the gtk.immodules (this is in different locations on different distros and versions, sometimes it's in /usr/lib/gtk-2.0/2.10.0/, but if not just find or locate it) configuration file with root privileges. Here's where I found it on my Debian 7 installation:
Then find the line that configures the cedilla and add an "en" option to the end so it looks like this:
A restart will be required before the change takes effect, and your cedilla's should be working properly :-)
